I remember one day that we were out on our boat on the Mississippi river between Minneapolis and St. Paul. There is a park right on the river on the east side. The road down to the park is long and steep. I saw the old cars milling around in the park, so I pulled in closer to take a look. It was one of the local Model "A" clubs there for a picnic. They were just leaving, and curiously a lot of them were backing up the hill in reverse. I found out later that unless you had an almost full tank of gas (or an auxiliary fuel pump) the gravity feed fuel system would starve out going up the hill unless they went backwards.