I was just an ordinary Joe, I'm not 100% sure but I think I collected my book from the post office and having the vehicle log book stamped. The vehicle engine capacity was on the front of the book. The petrol allowance would have been adjusted to suit the coupons as required. They were never used, but filling stations were running out of fuel. I worked for an haulage company, part time, if a lorry was going beyond its range it would carry cans of fuel to ensure it would get back.
I'm fairly sure my uncle used petrol coupons to fill up during the Suez crisis, when I was with him. I read in the paper, at that time, that a company was sending two lorries out to deliver goods then one would tow the other back to save fuel.