Since reading Lynn's article on saving gas by driving slower I have been trying to apply the tip to my daily commute. The problem is that these crazy Northern California highways are not very friendly to slow drivers. What I have been doing is driving behind big trucks in the slow lane so that I do not get honked at or pulled over by the highway patrol. Apparently driving behind big trucks also saves you gas due to something called drafting, and you can safely take advantage of this to save an additional 5 to 10% of your gas.

The science behind drafting is closely related to why driving slower saves energy. Basically, you have less air resistance in front of your car if a big truck has already passed through the air and your car is in the tunnel or "slipstream" behind it. A truck also blocks some of the air rushing at you. On the popular Discovery Channel show Mythbusters it was shown that if you follow a big rig by 100 feet you can decrease your fuel consumption by 11%. The daredevils went a bit further with the experiment and followed a truck at only 10 feet and managed to decrease fuel consumption by 40%.

As the MythBusters crew said, it is extremely dangerous to drive too close to a giant truck because the truck driver might not see you, and you may also be pulled over for tailgating. A safe follow distance at 55 miles per hour is about 160 feet to 240 feet since your car is travelling at approximately 80 feet per second and you want two to three seconds of reaction time to hit the brakes. If you are travelling faster you need to give yourself even more space. I definitely do not recommend dangerous driving behavior just for the sake of saving a bit of gas, but if you are driving slowly on a highway full of speed demons, safely following after a truck could save you gas and harassment.