Gas mileage improvements

Spurred on by a related post from wyoming_1, I’ve decided to finally post the results of an experiment I tried recently to improve the gas mileage of my truck on my daily commute.

I drive a 2007 Toyota Tundra 4-door pickup with a 5.7L V8, so as you can imagine, my mileage isn’t great. My average overall mileage before my experimentb was 13.13 MPG. As the result of some driving style changes, I’ve achieved 16.7 MPG, which is almost a 30% increase! That’s an easy $20 a month on my commute alone.

First, a little background. My daily commute is 6.9 miles one way, with 10 stoplights and speed limits of 30 through 55 MPH. It takes about 15-16 minutes on average. That’s all the truck gets used for, not counting trips to Menard’s and camping trips, etc. I would classify my driving style as average compared to the other vehicles on the road – not terribly aggressive. For the record, we also own a Mazda5, one of the most fuel-efficient 6 passenger vehicles available on the North American market, but this post isn’t about my choice of a vehicle. It’s about doing the best I can with what I’ve got, and hopefully what I’ve learned will work for you too.

To get accurate results, I measured my mileage by dividing the number of miles driven on a tank by the number of gallons required to fill it. My driving patterns didn’t change (mostly just driving to work) and the weather was consistent before and during the test, meaning I used the air conditioner about the same amount. I filled up each time using the same technique on the same gas pump at the same time of day. In short, all I did was use the accelerator and brake pedals as little as possible. I did set some rules for my experiment, however, to make the adjusted driving style usable. After all, I’ll bet if I drove 25 mph everywhere I went I could get great mileage, but I wanted a practical technique.

  • Limit engine speed to 1500 RPMs (that’s my engine speed in overdrive at 60mph – this figure won’t be appropriate for smaller engines)
  • Always obey the speed limit
  • Drive at the speed limit on extended stretches
  • Don’t upset other drivers (except those who are being jerks anyway)

While following those rules, I was able to employ the following techniques and tips:

  • Use the brakes as little as possible.
  • Coast as much as possible, especially to red lights.
  • Don’t brake at turns any more than you have to to remain safe. Preserve your momentum!
  • Accelerate at a rate of 1.5 MPH per second. That means it’ll take you 20 seconds to accelerate to 30 MPH. This is very leisurely, about like a loaded semi.
  • Use cruise control.
  • Learn the timing of your usual traffic lights. There’s no point in speeding up to a light that you know is going to stay red for a while. Try to roll through on green no matter how slow you’re going.
  • Choose a time of day where traffic is conducive to this driving style. For me, 7:15am is great and 7:00am is awful.
  • Choose multi-lane roads when possible so impatient drivers have a chance to go around you.

Here are some other observations from my experiment:

  • Most drivers are content to fall in line behind me instead of racing around me.
  • Even in gear, I can coast a long distance with only a minimal loss of speed.
  • If I start at 30 MPH, I can coast the last four blocks to my house, around two corners and into my driveway, losing only 10 MPH.
  • Lots of drivers think it’s a race like to win the race to a red light, but we usually all meet up on the same red lights anyway.
  • When you drive a vehicle that can do 0-60 in under 6 seconds, it’s hard to do it in 40 seconds at first. After a while you get used to it, though, and it’s actually relaxing.
  • I’ve only had one driver get mad. I was in the rightmost lane out of three at a red light. He was behind me and expressed his dissatisfaction with my acceleration in a variety of ways. He was about 60 and drove a silver VW Turbo Passat. I haven’t forgotten his license plate number yet.
  • My new driving style has added less than a minute to my commute.

There are some other techniques I’d like to explore to improve this figure further, but so far my results have remained consistent. I’ve got a ScanGauge II on order. Once I get it I’ll be doing some more experiments, such as the controversial use of neutral and different tailgate/tonneau configurations.

I’d encourage you to give some of these tips a try. If your results match mine, your savings will be the equivalent of today’s $4 gas dropping to less than $3!

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  1. … I am more and more thankful to not own a vehicle. On the other hand, if the airlines could figure this stuff out, my flight home at Christmas (which 2 years ago was less than $100) is now over $200. I may have to skip Christmas LOL.

  2. Coast downhill (and any other time you can) in gear, not in neutral. In gear, the truck’s motion will keep the engine turning, so the injectors get shut off. In neutral, it obviously needs fuel to keep the engine running.

    YTD my ’03 Subaru Outback is running about 20% better than EPA estimates for mileage. My mileage got noticeably better when I switched my coasting from neutral to in-gear.

  3. Andy – awesome! Thanks for the info. What you’re saying is what I was guessing would happen, but I didn’t have any way of proving it. I have to descend a large (by Illinois standards) hill every day, so I crank down it at 4000 rpm in second gear. I was hoping that wasn’t blowing through extra fuel.

    20% better? That makes you a certified hypermiler. I’m looking forward to doing the same.

  4. I wouldn’t go so far as to call me a “hypermiler” – I’m not doing all the drastic things they’re doing. I’m just doing some coasting and pulled the roof rack.

    But I am quite proud of getting such great mileage out of the car when others are struggling to get 25 on the highway.

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