MPG in Congested Highway Traffic

"Voice of C. Montgomery Burns" (voiceofcmb) 07/20/2015 at 14:41 • Filed to: None

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I recently went from a commute that was 95% highway to another commute that is also 95% highway. However, the first commute was a congested route that I had to endure and the second route is almost always smooth traveling at highway speeds (toll highway).

I’m a guy that’s obsessed with numbers and I’m cheap, so I’m trying to calculate where I stand after moving from the congested route (that is free) to the smooth route (that is toll).

I can venture to say that my MPG on the smooth route, depending on how heavy my foot is, will be close to the EPA highway MPG so that is the assumption I’m making for the toll road.

I can’t seem to find any agreed-upon hit to your MPG or equation to calculate your MPG for congested highway traffic. We’re talking average speeds of 30-35mph on the highway, with random stops and goes, level of congestion.

Has anyone done the math? Is congested highway MPG closer to the EPA city rating, EPA highway rating? The middle?

Sam > Voice of C. Montgomery Burns 07/20/2015 at 14:47

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A big part of that depends on the gearing in your car. My BMW hated stop and go and the empeegees would drop to around 15 from an average of about 18. Meanwhile, my Porsche is a lot better in stop and go, since highway speeds are cruising at 3500RPM and in stop and go I can keep it below 2.5k.

cazzyodo > Voice of C. Montgomery Burns 07/20/2015 at 14:56

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I’ve had instances where my average speed of 15mph, maybe, came out to be highway mpg and my highway travel mirror city mpg. The first instance stands as a damned miracle in my head.

450X_FTW > Voice of C. Montgomery Burns 07/20/2015 at 15:56

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Target your combined number then for FE. Since your new route is about as combined as it can get with the stop/go of toll roads

Voice of C. Montgomery Burns > 450X_FTW 07/20/2015 at 16:13

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I use EZPass. There is no stopping on my route. Literally if I hit the right lights, I can get to work stopping less than 5 times.

450X_FTW > Voice of C. Montgomery Burns 07/20/2015 at 16:28

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big thing to remember is that your FE is going to decrease exponentially compared to vehicle speed. Cruise control is your friend for good FE

Stang70Fastback > Voice of C. Montgomery Burns 07/20/2015 at 17:04

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Consider that stop and go in city traffic is a lot of hard acceleration and braking as you try to beat lights and cut off other cars to get places first.

Stop and go on the highway is MUCH more leisurely since you’re just plain stuck. Acceleration and braking is much more casual, and as a result your mileage will be significantly better going the same average speed in highway traffic, than a similar speed in a less-congested “city” environment.