There is also a claim floating out there the reasoning why generally European cars place them on the passenger side ( or both sides for some British cars) . The idea behind this was for safe refueling on the side of the road if the car had an out of gas situation. If you look at Ford's products that originated here, they usually are on the left ( F-150, Bronco) . However, If you look at the Ford cars that were adapted from Europe or are a staple in the Euro market, the tank is on the Right. I guess we will never know.