Had a fullsize reservation (using free days) last week and was given a choice of Malibu, Altima and Lacrosse at the counter. Took the Lacrosse, and then had to return it back after five minutes due to an AWD system failure.
Ended up with the Malibu as a replacement - base LS model, which I haven't seen before at National. Most of the other cars in the lot were indeed GM models.