Cars Across the Desert Puzzle

The Puzzle:

Cars Across the Desert

A car has to carry an important person across the desert.

There is no petrol station in the desert and the car has space only for enough petrol to get it half way across the desert.

At the start depot there are a dozen identical cars that can transfer their petrol into one another.

How many cars are needed to get this important person across the desert?

Do you have the answer? Check against our solution!