Hertz - Rant: I *never* get upgraded

So I've been a totally loyal customer of Hertz for years...can't even remember the last time I rented from anyone else. I have been renting Lincoln LS's, mostly at SFO, frequently (once a month or more) since last fall. They must recognize me as a repeat client, because my car is just about always in the up close PC spaces (I'm only 5*), but....not once during this time have I been upgraded! C'mon Hertz, how about throwing one of those nice Audis or MBs that SFO has my way once in a while?

On a more serious note, am I doing something wrong or is it just luck of the draw.

When you rent Prestige (like the LS), they assume you want that car.

I have never been upped on Prestige - always get exactly what I requested.

i work for avis, but most rental companies in the higher end categories won't upgrade you unless you ask because of sea_tigger's answer, usually those who rent high end want that specific car. try asking if they have an upgrade available, and say "ive been renting for a while, I want to see if my rental status is good enough to merit a comp upgrade."

as with anything, you never know til you ask.