Aah, okay now I follow you better. Yeah Enterprise tried that one on me once. I have a free rental cause they screwed up a previous booking, and I had booked an Economy but had a free upgrade coupon. The agent gladly took my coupon and said he'd do even better and put me in an Intermediate (I got a Pursuit with a sunroof, fairly loaded for E-Prise). Things is, they had no Economy or Compact cars to speak of. When I tried to raise the question, he quickly focussed on his computer monitor and then came up with 3 great ways I was getting a heck of a deal:

1. I got a lower rate than they were normally quoting (I wasn't paying anyways and it's the rate they were posting online)
2. I got a double upgrade for no charge (Read, a mandatory upgrade as they had small cars and they still stole my coupon)
3. I was getting it for free (Like I said, cause they had no car for me and I missed an important engagement since everyone in the city was sold out)

So yeah, I guess it's one thing for a no-frills like Enterprise to do that, but I wouldn't expect it of Hertz. A one-class upgrade is just that. When you book, you expect to be getting something slightly larger, hence you book a class lower than you want. But unfortunately I find a lot of rental agents are merely robots programmed by whoever is running the place. I swear you could tell them a Hyundai Accent is a full-size specialty car and they'd defend it to the grave, even with a PC member.

Anyways, I digress. I love the car choice at National, but unfortunately we only have 3.5 locations in Canada with that and not even the traditionally Emerald Aisle/Executive Selection. It's the equivalent of Emerald Reserve. The half-location is YYZ, where you get your choice of cars unless the agents panic and swipe all the keys, effectively making it counter service.