I not sure that it's so much that it's illegal (although as the MOT test measures the safety of all fuel tanks and lines it may be) but no petrol station in the country would be allowed to serve you as they are not allowed to authorise the sale of fuel if the customer has the nozzle in the defined interior of the car. You cannot even fill up your spare petrol can if it is in the boot but must take it out and put it on the floor.
Correct me if i'm wrong but i used to service Land Rovers and some of them have the tanks under the front seats and to fill them you had to lift the seat up.
I am still trying to fin the website, but as far as i can remember it is illegal to have the filler cap inside the cab, unless fully ventilated, after April 1st 1995.
For rally cars they have to have a drip catching tray around the filler cap that drains outside the car, a breather that vents outside the car and cut off valves that shut off when the car rolls.
