I would rather spend a bit more for gas and drive safely. When you are behind a big truck your field of vision is blocked and that is very dangerous. 3 seconds or 240ft behind a truck is not enough of a space cushion to prevent a crash.

AAA says "at highway speeds, a 2- to 3-second following distance will not give you enough time to stop if the road ahead is suddenly blocked. At 55 miles per hour, you would need at least 4 to 5 seconds to stop the vehicle to avoid something in your path of travel. Therefore, your position in traffic should be based on availability of escape routes."

AAA further says "If your vision is blocked by a large vehicle such as a SUV, van or truck, increase your following distance to 4 seconds. This extra distance will give you better visibility."

"Drivers must learn to look at least 20 to 30 seconds ahead. At highway speeds of 50 to 65 miles per hour, the 20- to 30-second visual lead time translates to one-third to one-half mile," says AAA.

Be safe on the roads!