Bikes & Cars...

DriveFlexFuel.com sells conversion kits for cars, trucks, RVs, motorcycles, and boats so that they can run on E85, gasoline, or a combination of the two. The kits are available for any fuel-injected engine (which covers a lot of ground) for a few hundred bucks.

As a hypothetical demonstration, I’ll use my little red GMC pickup truck. The picture of this particular conversion kit looks intimidating: a box with a lengths of...