I'll be flying into SAN for the first time and using Alamo as always.. What types of midsize cars do they use? Is it Impala's like they have in PDX?

One time I was lucky enough to be given a free upgrade to a Prius for no extra charge with a standard midsize reservation.. I typically drive a couple hundred miles on that trip so it saved me a fortune in gas! Is that typical, and has anyone else gotten that as well?