Originally Posted by
knighthawks97
Car companies differ from hotels and airlines in that a credit card/purchase is not required to guarantee a reservation, and it seems like the availability on the reservation system is VERY different from actual inventory.
Though airlines/hotels may fall short sometimes on delivering "what was guaranteed in your confirmation," they are FAR more reliable in that aspect than rental car companies.
Car rental companies probably got away with it for so long (at least in the US), because people in the US have generally perceived that "bigger is always better" when it comes to cars, so a car rental company can oversupply the larger size classes and satisfy everyone by offering "free upgrades" when the reserved smaller cars are sold out. High fuel prices obviously break this assumption.