Monday, May 14, 2007

For my car, after experimenting with different driving styles to see what works best, I'm now getting 26–27 mpg city and 31–32 mpg highway at 75mph and 32–33 mpg at 65mph. The EPA rating for my car is 25 city / 31 highway. However the EPA is now lowering all of their estimates to match the average driver, and with the new estimates, my car is listed as 22 city, 29 highway*. This might make people feel better about their own driving habits instead of making them think about improving them.

High gas prices are what leads many people to look at gas mileage, but gas prices are not that important. Everyone looks at gas prices because they're printed in big bold numbers at every gas station. Fewer people look at the gas mileage. Learn techniques for using less gas while driving. When the light turns red, take your foot off the gas. Watch for light timing (many lights are timed so that if you drive at the speed limit, you'll get more greens.) For city driving, don't accelerate quickly, and don't drive so fast. Your driving habits make more of a difference than which gas station you go to. And even fewer people look at how much they drive. Plan ahead. Reduce the number of trips you take, and combine multiple errands together into one trip. Move closer to your workplace (this is one reason renters are better off than home buyers—a topic for another blog post). If you're looking to save money on gas, how much you drive is probably the place you should be looking first. Keep track of miles (or gallons) per week.

It's nice to see the EPA adjusting the ratings, but the lower estimates don't match what I've measured with my own driving. The old estimates match closer.

* This is just an estimate that doesn't take into account wind resistance. My car's coefficient of drag is 0.31, and as a result my real-world highway gas mileage is higher than the estimates. It might be better to take into account drag area as well.

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2 comments:

Rick C wrote at Wednesday, May 23, 2007 at 9:39:00 AM PDT

I drive a 12-year old Ford Escort. It gets--actual, measured mileage, computed by keeping track of amount of gas pumped and the odometer reading--of around 30mpg highway, and 20-25 city, depending mostly on the amount of stop-and-go.

I could get a newer car with higher mileage, but the current options that aren't highly expensive (for example, if I had $30K I could get a Ford Escape hybrid) aren't really big enough for me, my wife, two kids, and a medium-large dog.

Amit wrote at Tuesday, May 29, 2007 at 11:02:00 PM PDT

A friend of mine points out that I intentionally choose city roads that have fewer lights and stop signs, and that's likely why my city mileage is high. I tried driving on more “normal” streets, and my mileage dropped to 23, so I think he's right about this.