1956 Chevrolet Convertible My father has, over the years, restored his magnificent 1956 Chevrolet convertible to near perfect condition. Last weekend, he decided to go on a little spin ('twas a warm day, perfect weather for a convertible). As he was pulling out of the driveway, he noticed he was low on gas - the gauge was practically on empty.
On his way to the gas station, he made a quick stop at the local fast food restaurant. Having nowhere to park, he reluctantly stopped his car down a side street. As he was leaving, he noticed a few young guys eyeing his vehicle. Thinking nothing of it (it's rare to see this model car in such good condition, so people typically stare), he walked into the food establishment to get himself a deliciously awful burger.
The line was long, so it was a while before he returned to where he parked. He returned to his worst nightmare: his car was gone.
He hurriedly called the police and reported his Chevy convertible was stolen. He then went back into the restaurant and ordered a half-pounder with bacon, to go.
About 15 minutes later, the police called him back. Apparently, right after he called, the police received a call from a female worker at a gas station about a mile out of town. The worker reported that a beautiful car was left nearby. She said three young men drove up and prepaid for $20 of gas.
The three men walked around the vehicle many times, checking under the hood and in the trunk. After a couple minutes of studying the car, the men left without filling up. As they were leaving, the car ran out of gas near the gas station. The men left it there and took off running. The police couldn't think of a reason for the young men paying for gas they didn't use. My father, however, knew exactly what happened.
The question is, why would the three men pay for gas they needed but didn't use?

HINT: The type of car is very important.