Originally Posted by Jason F Potvin

The reason I ask is because local experiences sometimes trump broad generalizations. I'm only a Preferred Plus (/Avis First) member at Avis, but have been given BMW 3 series, 5 series, X3, X5, Audi A4, Q5, Mercedes C63 AMG, Range Rover, Chevy Camaro SS, etc. on Fullsize reservations.
ALL without paying for an upgrade.
I have a higher status level at Hertz and a CDP that gives an additional upgrade (even though Hertz Collections aren't supposed to be included, that's very YMMV), hence the question.

Maybe your experiences haven't been as fruitful. Sometimes it pays to be nice and ask.