In Defense of Diesels (For You Petroltrolls out there)

"Group B-raaaaaaaaaap!" (AbarthGuy) 09/06/2013 at 16:05 • Filed to: OilBurners

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To expound upon !!!error: Indecipherable SUB-paragraph formatting!!! , specifically for those who will try to use the base cost of No. 2 Diesel as an explanation for why it's not as economical as gasoline, here is the math which will systematically quantify the value of Diesel ownership. Due mostly to my own vanity, I have chosen to submit my own 2000 VW Jetta TDI against a similar Gasoline-fueled Jetta. The TDI is a 5-speed with 1.9L turbodiesel motor, and the competitor is a same year 5-speed 1.8L petrol turbo.

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Here are the current EPA estimates, courtesy of !!!error: Indecipherable SUB-paragraph formatting!!! .

Immediately, we see that there is already a 58% economy advantage to the TDI. While this advantage is on the high side in relation to other Diesel v. Gas comparos, it's not out of the ball park. It's worthwhile to note that this is based on the EPA's current mileage calculation methods, and not the ones they used before 2007. This is what the window stickers used to read as:

(The EPA's current mileage calculations are more accurate, unless it's for a !!!error: Indecipherable SUB-paragraph formatting!!! . But since the revision has culminated in lower window-sticker MPG's, people think cars are less efficient now. Of course, they are right to an extent, as cars are heavier due to stronger safety systems and more equipment on board. I sell FIAT's. Even with an EPA sticker of 40 MPG in the window, people see the size and assume that they should get 150 MPG because they "used to drive a Metro, and that got, like, 60 MPG." They in fact, did not get 60 MPG. They probably got 35, and gas was $1.09/gallon back in the 90's, so they felt like they got 60 MPG. There is a point of diminishing returns on fuel economy, and to produce the performance the American market dictates, fuel economy is always sacrificed, especially in A/B Segment cars. But I digress. /siderant)

So we've set the baseline for performance. But what about the disparity in fuel prices? Great question. Using current to this minute data from our old pal !!!error: Indecipherable SUB-paragraph formatting!!! , I know that in my area Regular Unleaded is $3.65/gallon, Premium Unleaded is $3.85/gallon, and No. 2 Diesel is $4.09/gallon.

Now for the maths, as it were. At $3.65/gallon, a 24 MPG Jetta costs roughly 15.2¢ per mile. At $3.85/gallon for Premium, a 24 MPG Jetta costs 16.0¢ per mile. And at a whopping $4.09/gallon, the 38 MPG Jetta TDI costs 10.8¢/mile. That is about 30% total savings over just regular unleaded, despite costing 12% per gallon.

Now, let's extrapolate:

At 15,000 driving miles per year, the Jetta on Regular Unleaded will cost $2280 to operate.

At 15,000 driving miles per year, the Jetta on Premium Unleaded will cost $2400 to operate.

At 15,000 driving miles per year, the Jetta TDI on Diesel will cost $1620 to operate. A savings of $660 per year over the similar car on regular unleaded. This doesn't even factor in the loss of efficiency which occurs when one runs an engine designed for Premium fuel on Regular (figure no less than a 10% drop).

Since we also know !!!error: Indecipherable SUB-paragraph formatting!!! , then buy purchasing a diesel Jetta, I will have saved $7524 in fuel costs.

Now, I know what you're thinking. "This all sounds good, but diesel options, when available, are way more expensive." Well, I took this into account as well. While the TDI is now a bit pricier than a similarly equipped Jetta SE (The TDI doesn't come in S trim anymore), back in 2000 the GLS TDI was actually cheaper than the GLS 1.8T. Observe the original MSRPs:

Add that to the fact that the diesel engines are incredibly reliable due to their overbuilt nature (because part of the ignition sequence of a diesel requires extreme pressure, the blocks and heads on the TDI's have to be bullet proof, and they are!), there is another gain in the important, but difficult to quantify, cost of ownership. But in fuel alone, I will have saved enough in 11.4 years to pay for a sweet used project car, or a kick ass wave runner or snowmobile, or whatever else my 32-year old adolescent brain could think to squander $7524 on. And even if going by today's market standards and having to pony up an extra $4200 to jump from a 2014 Jetta SE to a 2014 Jetta TDI, I'd still have an extra $3500 burning a hole in my pocket. No matter what, diesel will always be the cheaper option (apples to apples, that is).

Or go buy a FIAT 500. They get diesel-like mileage with gasoline.

deekster_caddy > Group B-raaaaaaaaaap! 09/06/2013 at 16:10

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A couple of thoughts -

Diesels tend to run for more miles without needing major repairs, but when major repairs are needed they tend to be more expensive. Typically fuel delivery issues versus major mechanical issues.

As far as justifying the cost goes - Some people will buy a car purely because of it's cost to operate, but we on oppo know there is much more to owning and driving a car than just it's operational cost.

Final thought - what's the difference between "quantify" and "justify"? I almost used them interchangeably.

Slave2anMG > Group B-raaaaaaaaaap! 09/06/2013 at 16:14

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I did these same sort of calculations back in 2010 to make a case for my company to lease me a Jetta wagon TDI. On running costs along, 25K/year miles, it was about $900/year less expensive compared to a four cylinder Accord. And despite being a better equipped car the TDI was about the same/month to lease due to higher residuals...and in May VW came after us and threw $750 at us to turn the thing in 60 days early as they wanted it, 70K miles and all, for the used lot. Where it stayed for 9 days before being sold...

Great car, I loved it except for it being a bit narrow inside. Never squeaked or rattled or gave me a moment's trouble of any kind. The TDI pulled like a tractor on mountain grades, cruised effortlessly at 80 mph, and still did 42-43 mpg.

Group B-raaaaaaaaaap! > deekster_caddy 09/06/2013 at 16:30

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Good points, to be sure! My general thought on this subject has more to do with how the average non-Opponaut would drive a car, which is "like an appliance". I feel that for commuter use, the diesel represents one of the better options out there. While there certainly are diesel-engined cars for enthusiasts, the vast majority of sports cars are gasoline (and now hybrids, a la 918 and TheFerrari). So using the whole "Diesel is more expensive" argument as a reason for not buying a diesel commuter car is invalid in my eyes. That said, you wouldn't see me lining up for a turbodiesel C7 or GT3 RS. Probably.

For my intents and purposes, I use "Quantify" as a math-based derivative of "Justify". Same thing really, but with hard numbers.

Group B-raaaaaaaaaap! > Slave2anMG 09/06/2013 at 16:35

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My TDI is a second car that sees a lot of weekend duty, or as a loaner for friends. That said, she runs like a top. I do need to replace the EGR valve though. It runs well 90% of the time, but under heavy loads (like sustained acceleration uphill) the EGR pukes out and I lose the turbo. Combine that with the loss of compression over the years, and I start to lose speed up hills. Luckily turning the car off then back on again will reset the EGR valve. It will still cruise reliably at 80, though, and starts even on the coldest of MI winter mornings. 230,000 miles and counting.

deekster_caddy > Group B-raaaaaaaaaap! 09/06/2013 at 16:37

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I would consider a diesel for a long range commuter a good choice. I'm always concerned about diesels for short range driving (although newer diesels seem to have improved a lot in that regard).

Group B-raaaaaaaaaap! > deekster_caddy 09/06/2013 at 16:39

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The higher quality Ultra-Low Sulfur fuel that was phased in during 2007 helps a lot, too!

Tekamul > Group B-raaaaaaaaaap! 09/06/2013 at 16:40

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90hp vs. 150hp

You should at least address this

Group B-raaaaaaaaaap! > Tekamul 09/06/2013 at 16:59

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My support of diesel was mostly aimed at commuter use, not enthusiasts, only because that was also the aim of the Audi TDI advert which inspired the post. So performance is rarely an issue of concern for the commute use users. For those who suffer from "The Camry Effect", a diesel engine is actually a great choice for them.

Considering most people who view the car as a commuter appliance also are unlikely to test the limits of their car, a car with low HP but high Torque (like a TDI) will give a nearly identical experience to a vehicle with better HP and similar Torque. In the case of the dueling Jettas, the TDI generates 158 lb-ft, and the 1.8T generates 162 lb-ft. At commuter speeds, with slower acceleration, neither car is likely to crest 3000 RPM, which means the TDI will hit and maintain it's sweet spot for most of the trip, while the 1.8T woun't fully utilize it's available HP. Again, this is more for the surface streets than the race track.

I always tread lightly around HP v. TQ 'round these parts, though.

desertdog5051 > Group B-raaaaaaaaaap! 09/06/2013 at 16:59

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A friend has an '02 Jetta diesel and on a trip to Vegas (600 miles) and no wind, he averaged 49 mpg at 75mph.

Group B-raaaaaaaaaap! > desertdog5051 09/06/2013 at 17:05

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Not the fastest car. Not the sexiest. Not the loudest. Not the meanest. Not the most exciting. Not the poster on a 12-year old's wall. Not photographed with centerfold models sprawled across the hood.

But dammit, they're efficient!

Tekamul > Group B-raaaaaaaaaap! 09/06/2013 at 17:16

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At commuter speeds...neither is likely to crest 3000 RPM

This sounds like someone that isn't trying to enjoy their commute...or they live in central California.

I'm fortunate enough on my meager 7 mile to commute to bang into the rev limiter a couple times. Always worth it.

HammerheadFistpunch > Group B-raaaaaaaaaap! 09/06/2013 at 17:24

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as a tdi owner I've done lots of these calculations...then I stopped and realized its just a good car with great driving characteristics and operating costs at least on par with the best pure gas cars on the road.

Group B-raaaaaaaaaap! > Tekamul 09/06/2013 at 17:43

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Same here! In an Abarth, I get the world's most satisfying exhaust note. In the TDI... well, redlining at 5,200 isn't exactly heart pumping. But it still boogies!

Yeah, judging by the other drivers that I routinely get stuck behind, I think they all must've been taught that anything over 2,500 is bad for the car. Because they certainly don't seem to want to crest that. Of course, they are probably automatics, too, so the concept RPMs is moot.

Group B-raaaaaaaaaap! > HammerheadFistpunch 09/06/2013 at 17:47

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Good point. I try to spread the gospel of Rudy to future generations, mainly because I want to see TDI's to continue in production. I thought this would be a good primer for those not in the know about oilburners. When I squeeze 500+ miles out of a 13 gallon tank, I get quite excited.

That said, there is only one diesel-related issue which makes my blood boil: Gas stations with only one diesel pump, and it's on one of those dual fuel units. It drives me nuts to see 13 open pumps at a 20 pump station, and still have to wait behind two gasser CUVs who want to use the Diesel/Gas pump because it's the closest to the exit.

DoctorNine > Group B-raaaaaaaaaap! 09/06/2013 at 17:58

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Actually, your calculations left out the fact that the EPA mileage for gasoline vehicles is evaluated with 100% gasoline. So it will always overestimate your MPG, since the actual mileage you will get from pump gas (E10 -which has 10% ethanol) has to be substantially less, due to the fact that E10 has less energy per gallon than pure gasoline.

Group B-raaaaaaaaaap! > DoctorNine 09/06/2013 at 23:12

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This raises the question as to why the EPA doesn't test with standard pump gasoline. Have they stated why?

DoctorNine > Group B-raaaaaaaaaap! 09/07/2013 at 11:41

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It really does, doesn't it?