There is a small error in the spec that is causing lots of confusion. To make it easier, please modify the speeding formula. It says now (3 * gas - 50).
Please change it to (3 * gas_max - 50) where gas_max is a maximum of gas that the car can carry. Let's assume that gas_max is always > 15.
It is your design decision. Whatever you choose, you have to handle errors.
BON without explanation is 1/3 of the mark (no code is required for design questions from part 2)
Do not include any code of Cars in your report. Eiffel implementation has to be submitted for Cars, so it is redundant!