United States
We recently hired a car with Alamo at LAX and plumped through prebooking for the smallest and cheapest. On arrival they wanted us to trade up to a bigger car (apparently a Focus not being a family car).
When we got outside to choose a car there were only huge cars anyway, so there's no point in paying for the upgrade. There were also lots of Prius sitting there as midsize cars but, because the European families were scared of the unknown, went unpicked. Read up on them before you go if you want a trendy midsize car.
Search Been there