Tailgating and Hypermiling
Some drivers have been known to draft behind other vehicles, particularly tailgating larger vehicles, to save fuel. For example, hypermilers using this technique can achieve 75 mpg or more (a 10% increase in efficiency of certain hybrid vehicles). Some sources say that the most common tailgating does not save gasoline even at freeway speeds because one is likely to accelerate and brake so frequently that any aerodynamic savings are lost through the brakes. On the show Mythbusters, drafting behind an 18-wheeler truck was tested and results showed that traveling 100 feet (30 m) behind the truck increased overall mpg efficiency by 11%. Traveling 10 feet (3.0 m) behind the truck produced a 39% gain in efficiency. Of course, they warn that this type of driving "is insane" because the truck's blind spot is in that area, and if the truck stops quickly there is much less time to react. Truckers are not fond of the extra stress this puts on them, worrying about cars on their tail. Additionally, it can be very dangerous for the following car if one of the truck's tires (or their recaps) delaminate, as the chunks of ejected rubber can be large enough to cause serious harm, even death, to a driver following too closely.
Read more about this topic: Drafting (aerodynamics)