The price differential in car rental charges that bear no relation to the price of the car.
Once a year, we hire a 7-seater MPV (like a Ford Galaxy) so we can take my 80-odd y/o parents away with us for a long weekend. So we need a MPV to fit all 6 of us in. And every year I get pissed off at the pricing.
Can hire, say, a Corsa for about £100 for 4 days. The Corsa starts at £15k to buy.
A Galaxy starts at £33k to buy. Just over twice the price, so it wouldn't be unreasonable to think the hire price would be just over twice that of a Corsa. I know I'm being simplistic and there's more things to consider, but you wouldn't think there'd be too much of a difference to that 'just over twice the price'.
Yet you won't be able to hire a Galaxy or similar for less than about £450, with most hire companies wanting over £500.
It's hannoying.