Mileage Test

With gasoline prices approaching $5/gallon (my car drinks the premium stuff), I decided to try and see how driving habits can affect mileage. I read/heard that the slower you drive on the freeway (safely), the better your gas mileage. So on my weekly nighttime commute from Orange County to Torrance, I tested to see if speed affected mileage.

Both times I tried to set the cruise control and not touch the brakes. The route was the same: 55S/22W transition, 22 West, 405 North, 110 South, 223rd Street exit.

Trial 1:
Saturday, October 6
Average speed = 59.6 mph
Average mileage = 32.4 mpg

Trial 2:
Saturday, October 13
Average speed = 67.4 mph
Average mileage = 30.5 mpg

The data was from the onboard trip computer; I reset the counter at the beginning of the trip. Before this, I had never reset the computer, and my average mileage was ~23 mpg over 29,000 miles of combined highway/city driving. I was surprised at the high mileage numbers since my car is pretty large and has a 300 hp V6 engine. I was also surprised that I got a 2 mpg improvement by driving 60 mph instead of ~70 mph, even though it was a bit scary to be the slowest guy on the road. Finally, changes in velocity also affected mileage. The effect was most evident when I had to slow down for the 405N/110S interchange since it was a big right-handed loop. I probably had to slow to ~35 mph, then accelerate back to speed. The drop in mileage was ~0.2 mpg on the computer display even though I've driven ~35 miles.

Save gas, drive slow(er)!