Help Needed: Correct My Analysis!

"E. Julius" (soonerfrommi) 02/26/2015 at 10:16 • Filed to: None

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This is a chart comparing the current shortlist for my next automotive purchase in a number of areas. I did my best to compare them accurately but I have little to no firsthand experience with any of these, so any corrections would be greatly appreciated. I'm mostly concerned with the relative values, e.g. is a C4 Corvette more reliable than an E30. The actual number is meaningless, just an assessment of how close something comes to meeting my optimal expectation in a certain field.

I'm also open to any suggestions of cars that you think would be better than whatever is on this list, although they must at least have a targa or T tops. Honestly as it stands I'm pretty close to chucking the W124, but I figured I would give it a chance to redeem itself if I was wrong about anything.

A little explanation of each of the fields to clarify:

Initial Cost: the higher number, the higher quality car I can get upfront within my budget (approximately 8,000–16,000 in 2015 dollars). I attempted to correct for regional variations. For example, since I'd likely be buying the car in Michigan, Corvettes will be easy to find than other places and convertibles a little harder.

Maintenance Cost: how much does it cost to fix something when something goes wrong. This is separate from reliability. I only allowed a slight variance for DIY maintenance since I have no experience wrenching at the moment, and thus wouldn't be able to reliably count on this to affect my maintenance costs.

Reliability: pretty simple—how often can I expect an issue that needs to be fixed.

Fuel Economy: once again, pretty straightforward. Since this would be a DD I biased more toward highway miles for a hypothetical commute, so keep that in mind.

Practicality: separate from fuel economy, this is pretty much a measure of a car's ability to carry people and things.

Fun Factor: mostly subjective. Miata scores the highest because it's small and a full convertible. I ranked the E30 slightly lower since I don't think the convertible will drive as crisply as the Miata. Despite not being a full convertible I put C4 at the same ranking because it's relatively fast and has a V8. Z31 and AW11 rank below those because they're small and tossable but not full convertibles. W124 ranks the lowest (although still good) because it's the boatiest of the bunch. Full convertible though, so that's a plus.

SidewaysOnDirt still misses Bowie > E. Julius 02/26/2015 at 10:19

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The AW11 is so much more practical than a Miata. It has twice as many trunks, both are bigger, and normal sized Americans can fit in them.

Aaron M - MasoFiST > E. Julius 02/26/2015 at 10:21

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Out of curiosity, are you using swing-weight analysis to come to a decision? It's a little math-intensive, but is designed for subjective rankings like these and allows you to do some sensitivity analysis on changing the rankings.

http://wiki.ece.cmu.edu/ddl/index.php/…

E. Julius > SidewaysOnDirt still misses Bowie 02/26/2015 at 10:22

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Really? Could I fit two small suitcases in them?

dogisbadob > E. Julius 02/26/2015 at 10:27

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third-gen F-body?

Maybe a 4th-gen with the 3800 might work.

Also, Toyota made a Paseo convertible for a couple years in the 90s.

SidewaysOnDirt still misses Bowie > E. Julius 02/26/2015 at 10:28

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Oh yeah, no problem. Here's the frunk (the battery doesn't actually live there unless you move it).

...and the trunk. The trunk's wider than a Miata trunk, but not much deeper or longer. Should still fit a couple of suitcases or your groceries no problem. The frunk's better for somewhat bulkier things if you pull the spare out, but both

E. Julius > Aaron M - MasoFiST 02/26/2015 at 10:29

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I've never heard of that before, but weirdly enough it looks almost exactly like what I was planning on doing. I stopped short of doing the full thing though since ultimately the relative weights of the categories will vary with whatever job/living situation I find myself in after I finish school. Obviously things like length of commute, salary, easy access to somebody else's car will affect the weights, and I think there's too many unknowns at this point to make a reasonably firm decision.

The relative qualities of the cars though shouldn't change too much in the meantime, so I figured I could get that step out of the way!

SidewaysOnDirt still misses Bowie > dogisbadob 02/26/2015 at 10:29

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Paseo? Really? I mean, I kind of like them, but you're recommending a gussied up/downsized Tercel to someone looking at E30s, AW11s, and Miatas. It's not in the same company at all.

Mattbob > E. Julius 02/26/2015 at 10:32

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no way is an NA miata more expensive than a C4.

E. Julius > dogisbadob 02/26/2015 at 10:32

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Hmm, the F body is a maybe, I'll have to do a little more research and pick one out that I like. The Paseo is FWD right? I don't think that's really what I'm looking for. Thanks for the suggestions though!

dogisbadob > SidewaysOnDirt still misses Bowie 02/26/2015 at 10:34

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Yeah the Paseo is basically just a sporty Tercel , but that means it should meet your requirements, very reliable, good mpg, not expensive to keep on the road, it has a backseat, probably good for your intended purposes.

The W124 and C4 aren't in that league, either :)

E. Julius > SidewaysOnDirt still misses Bowie 02/26/2015 at 10:35

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Are there removable luggage racks available? I'd like to take the car on some longer road trips so something like that would be extremely useful. I plan on getting one for a Miata if I do end up getting one.

E. Julius > Mattbob 02/26/2015 at 10:35

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No it's not. That's why it's ranked higher. Higher ranking = better, and I could definitely get a higher quality NA for less money than a decent C4, so the NA is ranked higher.

GhostZ > E. Julius 02/26/2015 at 10:37

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Do it all in terms of dollars instead of a vague index.

Calculate total cost of ownership with the following:

Initial Cost + ~Compound interest for the duration you expect to own it

- Expected Resale Value

+ Expected repair costs for duration of ownersip

+ Regular Maintenence for duration of ownership

+ Fuel Cost for the miles you expect to drive (if you have a 20mpg car that you would only drive on weekends, a 30mpg car you would have to DD is not nearly as fuel efficient)

+ Insurance for duration of ownership

That will give you roughly total cost of ownership for the car.

For practicality, take a list of features or things you can do (4 seats, trunk, trunk big enough for X, etc.) and check boxes for each car that can do these things.

For fun factor, do the same, but with things you care about fun-wise (good at autocross, power/weight, convertible, etc.)

Take the two numbers from practicality and funfactor, add them up. Then divide the total cost by that number, and that's your index value.

SidewaysOnDirt still misses Bowie > E. Julius 02/26/2015 at 10:39

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Since you're looking for a T-Top model, I doubt it. I'm not sure what it could connect to, but when I look up AW11 luggage rack, I'm seeing some really creative ideas. It looks like Toyota made some sort of roof rack specifically for the AW11 at one point ( http://www.mr2.com/forums/threads… ), but I don't know how available they'd be now, what prices they are, or if they work on all body styles.

Mattbob > E. Julius 02/26/2015 at 10:45

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ahhh, I got it now. I was reading it backwards.

E. Julius > GhostZ 02/26/2015 at 10:45

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Honestly I'm not sure I'd be able to find enough reliable and consistent data to do the kind of analysis you're suggesting. If you have a good idea of where I could find that information I would consider it. That being said, that type of analysis doesn't really do a good job of factoring in the relative weights of the categories. Since I'm really unsure of how much money I'll be making and what sort of driving conditions I'll need to face after I finish school, there are situations where any one of those factors could dominate the other two by a substantial margin.

MIATAAAA > E. Julius 02/26/2015 at 10:48

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A linear diagram usually uses a continuous value on both axes. It would be easier to read as a bar/column chart.

That's all the help I can be here.

E. Julius > MIATAAAA 02/26/2015 at 10:54

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I understand the basics of charts, but I disagree and I don't see how I could portray this as a bar graph. For instance, what would it look like when the AW11 jumps down from top of fuel economy to bottom of practicality? The continuous lines allows a quick assessment of how an individual element compares to its competitors, like how the W124 line is consistently below all the others. This makes it pretty apparent that it's the weakest of the group.

I might be able to do a stack chart, but all the segments would be the same size and would just change order, which would really be no more useful or usable than this chart.

Tohru > E. Julius 02/26/2015 at 10:55

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My dad had an '89 C4 targa and on a road trip averaged 34mpg on a tank of fuel. He usually got between 26 and 30mpg. He had the 6 speed, and the 89 was the last one before the LT1.

Also, the Corvette is more reliable than a Miata. It's a small Block Chevy that spends most of its time at a leisurely rpm. The digidash can be troublesome, but dad's worked like a charm.

E. Julius > Tohru 02/26/2015 at 10:58

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Wow! That's substantially higher than what I found, although I was searching the LT1 models. I'll have to see if I can corroborate that with forum posts or something. How much of an effect do you think LT1 vs. non LT1 would have? I'd likely go with a later model for various reasons, but if the fuel economy is vastly different I would definitely consider something earlier.

GhostZ > E. Julius 02/26/2015 at 11:08

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Initial Price :Craigslist, Kelly Blue Book

Discount: Interest on a savings account the size of the cost (usually around 1% a year) for the years you expect to own.

Depreciation/Resale: Hagerty Insurance database and prior year models resale

Repair costs: Look up common problems on forums and try to get a ballpark of common part replacements, and then if you can't do the labor yourself, calculate the labor. You could also use this: https://www.automd.com/repaircost/

Maintenance: Same, someone else has asked this on a forum and gotten a straight answer, just good some searching.

Insurance is tricky, but you can try finding free quotes.

Fuel cost is easy, just take the miles you drive a year, divide it by the MPG, times the price of fuel per gallon and then times the years you plan on owning.

For example,

A 1990 Miata is going to have $3000 initial cost. Let's say you want to own it for 5 years. A savings account at $3000 can gain about 1.05% APY, so the comparative cost for 5 years is $- 3160 .

Miata prices are on the rise account to Hagerty ( http://www.hagerty.com/valuationtools… ) I doubt it will depreciate, but will actually increase in value. So let's assume resale is going to be about $3500. So Net gain is $+ 340

According to AutoMD, a water pump replacement, timing belt replacement, and a fluid change is going to cost $360. So assume that maintenence has to happen for 5 years, and you'll get $1800 total cost. Bringing our total to $ -1460

Assuming the miata gets 30mpg and you drive 10000 miles a year, that's $6666 of fuel a year, bringing our total to $-8126.

I'm not sure about insurance, so you'll need to find a quote somewhere or estimate it based off your current insurance.

So your total cost is $ -8126 With a capital requirement (amount of money you'll need to spend in 5 years) of $10966 (no discount rate, total cost before resale)

Let's say the miata is a 10 on fun, and a 3 on practicality. So that's 13.

Index value is 11126 / 13, or 855.8

Assuming you calculate the total cost of ownership for say, a C4 Corvette, as being $14000, then for it's index to match it needs to have 14000/855.8 of 16.5. So it needs, say, a 8 in fun and a 8 in practicality to be "better".

You might find the how long you expect to own a car makes a huge difference in how much it costs. Some cars cost a less upfront but will kill you on insurance, depreciation and gas.

Now this is obviously a bit speculative and some features in a car matter more, but it's probably the most solid way to compare two cars like this.

I think what's funny is that you could own a miata reliably for ~$180/mo + insurance, it just takes a lot of upfront cash.

Tohru > E. Julius 02/26/2015 at 11:10

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Dad's had the L83 small-block, which put out 240hp and 345lb/ft of torque. The LT1 puts out 300hp and 340lb/ft of torque. It takes more fuel to make more horsepower. The L83's combination of lower horsepower and high torque lets it loaf around at low rpm not using a lot of fuel if you want. In 6th at Interstate speeds it was running under 2000 rpm. You can go 1-5 in town and it won't complain because it's got gobs of torque.

That's not even mentioning the biggest failure of the LT1, the OptiSpark.

nermal > E. Julius 02/26/2015 at 11:17

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No love for the R32? Seems like it would be a great fit.

Fuel economy is kinda crap, but it makes up for it with that glorious sound.

E. Julius > GhostZ 02/26/2015 at 11:25

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As it stands it's a good way to compare the cars in an absolute sense, but there's no way to account for the substantial range of scenarios I could be in when I'm done with school actually making the purchasing decision.

If I'm making something on the top end of my expected salary range, the cost could become a very minor factor without affecting the relative fun and practicality scores between two cars. I'd want a model where I could change one parameter, and for instance have the Miata beat the C4 in a lower income scenario but vice versa in a higher income scenario. Maybe if I did total cost as a percentage of income instead?

I'd also have to be able to modify how important the other factors are as well. I could live 10 minutes away from work and be able to use my girlfriend's more practical car at any time, or I could have an hour long commute and have limited access to a car with a trunk and four seats. There's just so many unknowns right now. Another commenter suggested swing weight analysis, which was pretty close to my original intention. I think that would work pretty well in this case, but ultimately it's so far off it would be almost a waste of time to put the work into either model.

E. Julius > Tohru 02/26/2015 at 11:26

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Well I'll definitely have to consider that in the future. Thanks for the info!

Devilishprune > E. Julius 02/26/2015 at 11:26

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I drive an NA miata and get about 24 MPG with primarily city driving.

I drove a friends 93 C4 vert for about 50 miles on the interstate mostly. In 6th, the engine will be at about 2500 at 75mpg (if I remember correctly). It ain't workin hard on the interstate. The instant MPG was around 32-34.

E. Julius > nermal 02/26/2015 at 11:29

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Needs to be convertible, or at least a T top. Cool cars though!

E. Julius > Devilishprune 02/26/2015 at 11:30

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Hmm so depending on highway/city split and traffic conditions they could come out decently close. I think I should definitely bump up the econ score for the C4 then.

nermal > E. Julius 02/26/2015 at 11:31

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Ahhh, missed that part.

BLCKSTRM > E. Julius 02/28/2015 at 20:47

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Just curious why an E36 M3 convertible isn't on your list? Or even an E46? $16k is enough to get an e46 M3 vert.

Obviously maintenance on an e36 will be a little easier/cheaper than an e46, but being newer should be a plus for an e46.

Almost everything I've done was just replacing wear items. I've broken a thing or two, though, but that was more my own fault. I HAVE had some things fail, but at the mileage you'll be looking at for an e30 you'll be looking at similar problems.

Certainly nothing worse than you'll be looking at with an E30.

E. Julius > BLCKSTRM 02/28/2015 at 21:07

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Good suggestions. To be honest I hadn't really considered them. Realistically, do you think they would make reasonable daily drivers? My concern is that while I appreciate a good car, I have lots of hobbies, so it would be hard for me to justify spending something like 2x what it would cost to keep a Honda Civic running just to have something like that.

I guess that's what I find so attractive about the Miata and the 300ZX. The enthusiast in me would be willing to sacrifice a certain practicality and a little bit of cash to have something fun, but the responsible adult in me doesn't think it would be that much better to spend more cash to have something like an M3.

Really the problem is that I only have experience with the two econoboxes my parents have gotten for me so far, so I have literally no idea what owning an enthusiast car is actually like and it kind of scares me. If I were to buy something like an M3, I don't know whether it would be like "don't go out to dinner so much and you'll cover the costs" or "your retirement savings will be off track if you want to own this car". So much uncertainty, so I waste time making stupid charts like this one haha.

BLCKSTRM > E. Julius 02/28/2015 at 21:51

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It seems pretty practical to me. I also have a big cargolies for the rack. I can also get an entire set of wheels in the back seat. All 4 windows down and the sunroof open is decently close to a targa (at least for me it is).

The E46 is different story, but there's a good reason people people make fun of the E36 M3 for being a bored-out 328i. Lots of the parts are shared with the normal cars, so it's not bad to maintain. The US motor is down 90hp on the final euro motor (321 vs 240), but again - it's a lot easier to maintain and fix. Oil changes are normal - use whatever you want, none of that $200 special/dealer-only stuff like with the newer cars. I mean, I'd suggest some kind of synthetic, but you should be doing that with whatever you get.

You can spend as much or as little as you want making it faster, but there are a lot of little things you can do one at a time that total less than $1k altogether that can get you 20-30hp, which is decently close to the original Euro engine (280hp). And you can keep going if you want, or just decide to be happy. And then there are all the suspension things you can do. And the great thing is you don't have to - it's pretty great out of the box. But it's like Legos - I don't think you can beat it as a platform to learn on.

Also, the LSD, good weight distribution, and snow tires make it a mean winter machine.

It's a good first performance car too because it's just on that ragged edge of power. You're not roasting the tires in the first 3 gears, but you have enough you can do a burnout or powerslide once you get the hang of it.

You said your price range was like $8-$16k, right? You should be able to get an amazing, low mileage, we'll-maintained E36 M3 for WELL within that range, and it should be as reliable as your Civic*. On top of that, if you look on the enthusiast forums you can probably find one that's had a lot of the right upgrades (not "upgrades") done for not much more.

*Keeping in mind that only really applies if you drive it as fast as your Civic - which it can do easily.

To be honest, it will encourage you to drive it hard, and of course the harder you drive it the sooner you'll wear out/break stuff.

E. Julius > BLCKSTRM 03/01/2015 at 04:41

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Thanks for that. I never really knew much about those, but from what you've said I'll definitely consider the E36 now. If only I didn't have to wait so long to make it happen haha

BLCKSTRM > E. Julius 03/01/2015 at 12:47

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It should definitely be on your list if you're looking at a C4 Vette.

Also, given your budget, why not look at an S2000? Convertible only, a 9000 rpm redline, great handling. And reliability is totally covered - it's a Honda!

An E36 M3 and a Honda S2000 are definitely more in the same performance class as a C4 Vette than an E30 or a Miata. And they may also be a lot less expensive - both to buy and to maintain - than you expected.

Both the Vette and the M3 have a decent amount of tuning potential. The M3's engine doesn't have the potential the Vette does, but the Chevy small block has more potential than any other engine on the planet, so that's not saying much. I can't comment on the S2000, though 240 hp from 2 liters at 9k rpm doesn't seem like it would leave you a lot to work with. But power definitely isn't everything, and it's far lighter than the Vette and M3.

E. Julius > BLCKSTRM 03/01/2015 at 13:19

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I did consider the S2000, but from everything I've read it seems like unless you're really pushing it it's mostly just a harsher riding Miata. I'm not a trackday bro or anything like that, I just want something cool and fun, maybe a little quick, that I can take the roof off of. For that reason tuning potential/modability isn't really a huge factor for me. Once I get a fun car and can actually start driving it on tracks and at auto crosses and stuff that may change, but for the time being I would prioritize comfort over pure performance.

The C4 is definitely sort of an outlier as it's in a totally different performance tier, but they're very common where I live and I've heard they're pretty easy and affordable to maintain. Once again though this is all guesswork for me—I simply have zero actual experience with any of the cars on the chart or that we've discussed. Makes it sort of tough.

BLCKSTRM > E. Julius 03/01/2015 at 13:27

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You know, there's one other thing that comes to mind that you need to take into account.

I had a 1992 Nissan Stanza before I bought the M3. It wasn't my choice, and I hated it. There's a long story in how I got the M3, but part of it was the Nissan was becoming downright dangerous.

It was a grandma car (literally) before I bought it. Super low miles for how old it was. It really ran great, but the whole suspension was shot.

The thing is, it didn't handle well in the first place, so I didn't care about keeping it up.

One of the first things I did with the M3 was drop $1500 on suspension refreshing - something I didn't even care about before.

We drove or Camry to 190k before replacing the shocks. I just didn't care.

A good car costs more in part because you take care things you ignored before.

E. Julius > BLCKSTRM 03/01/2015 at 13:34

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That is a very good point, and not something I've heard before. I'm glad you brought that up actually, because I've meaning to ask people to share stories about stuff like that. Ultimately I think what I'm going to have to do is just drive all of them over the next couple years, and then when I'm finally ready to buy just take the plunge with the one I like best. If it ends up being too much hassle for me I'll get something else.

BLCKSTRM > E. Julius 03/01/2015 at 15:56

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Let me know if you do an oppo post about it - I may miss it, but I'll definitely chime in.

It actually goes with the upgrade theme. You may not plan to do upgrades, but when you have to replace a part anyway - like motor mounts or brake lines - it's hard to not spend a little extra for the upgraded parts (polyurethane motor mounts, stainless braided brake lines).

Can you imagine putting stainless braided brake lines in a Nissan Stanza?

E. Julius > BLCKSTRM 03/01/2015 at 16:07

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Yeah I'll definitely post about it when I get a new car, but that won't be for a while (gotta finish school, probably buy a bunch of other boring adult shit first). In the meantime though I'll post some first impressions from any test drives I do, and I'm definitely getting a motorcycle when I get back to the US in May so you can read about that if you're interested.