The question was if heavier cars should pay more. Heavier cars are more expensive to buy, so this means that people who can afford a big car, will pay more. It's a sort of progressive taxation by proxy.
For context: don't forget that this isn't the US: not everyone drives an SUV/pick-uptruck. Here you can see the size of the most popular car in France, compared to a pick-up truck.
The question was if heavier cars should pay more. Heavier cars are more expensive to buy, so this means that people who can afford a big car, will pay more. It's a sort of progressive taxation by proxy.
For context: don't forget that this isn't the US: not everyone drives an SUV/pick-uptruck. Here you can see the size of the most popular car in France, compared to a pick-up truck.