Do you think driving carefully and using defensive driving techniques can net a huge improvement in fuel economy? It almost sounds to good to be true, but in my fuel economy challenge, I netted a 50+% increase in overall fuel economy.
Using purchases I had in my fuel logbook, I averaged eight previous fill ups (EDIT: BEFORE I started driving differently!). The fuel economy I had was 22.49 MPG. The worst fuel economy I had was 19.05 (ironically, the first tank I owned the car was the worst fuel economy, and the best was the second tank). Over the next months, my fuel economy ranged between those two and averaged 20.46 MPG, nearly identical to the newest EPA ratings of my vehicle, which peg combined mileage at 20 MPG (18 city/26 highway).
The last couple tanks I've been trying to use defensive driving techniques to maximize my fuel efficiency and to see how high a number I could get. Its quite impressive!
The techniques I used most: limited (slow) acceleration, using cruise control set to near the speed limit (or slightly slower than the speed limit on highways), and coasting as soon as a light I could view turned red. While coasting was very difficult to do (many people would tailgate me, then pass me, and eventually stop at the light), I found that once people behind me understood what I was doing, they followed my technique. In the city, it would likely take me 5-10 seconds to hit 35mph.
Since my vehicle has a standard transmission, I would also frequently skip gears to go to a lower gear and benefit from lower RPMs. The less the engine rotates, the less fuel it needs. A technique I could have employed but did not: shutting engine off at a red light. It was tempting to try, but I elected not to.
Overall, the outcome of the techniques and being less in a rush set me back very little in terms of time- I noted I frequently caught back up to people who accelerated at a high rate.
My first tank of utilizing these techniques I achieved an overall economy of 31.22 MPG! Pretty impressive if you ask me. I eventually got 435 miles on one tank of gas (nearly 14 gallons) which was nearly 53% better than my previous average combined mileage.
My second tank driving defensively I achieved an overall economy of 30.77 MPG. Again, considering that I continued to use A/C (and its been hot here!) I'm happy with this number. I got 423 miles on this tank (13.75 gallons) which was again over a 50% improvement vs. prior tanks.
My third (and last tank) driving this method netted my lowest of the three trials (perhaps I was getting eager to go faster quicker). This time, overall economy was 29.82 MPG. The heat continued, and I used A/C nearly the entire time. I could tell towards the end that I was accelerating at a slightly quicker pace. I got 412 miles on this tank (13.8 gallons), which was still a 45%+ improvement over my average.
Over three tanks of driving defensively, using said tactics, I drove 1270 miles. Typical driving would have netted me 855 miles or so, an improvement of 415 miles! That's like buying two tanks of gas and getting the third FREE! If the entire U.S. drove like this for a month, we could probably lower our demand by at least 10%.
So... a challenge for all of you- drive defensively for TWO tanks of gas and see what kind of improvements you see. It won't necessarily be fun to drive, but it will be much more relaxing, and I'm sure you won't hate spending less money on gas!