I don't know about no car. I had a car from 1987, namely a Ford Escort, that was incredible good on fuel. 40MPG on a trip was not uncommon and at least 30 MPG local driving was the norm.
A large SUV is of course quite lousy on fuel, but fully loaded with family, luggage and a rack with 4 bikes is an impossible task for the Escort. Plus if there is a creek to be crossed, the Escort would have to float it.
Ah, I didn't know that. Not particularly a fast car (although it is quick for what it is), but all EU cars are made to run on 95 RON fuel. Anything lower than that and most cars would run pretty lumpy I would have thought, with them pre-detonating the fuel/air mix.