And then there is the advantage of taking a chance and deliberately corrupting plans.
I've been known to reserve the cheapest econobox possible, which are often the first ones to go simply because they're cheap. Then I dawdle on my way to the rental car counter and take what they have left. This choice generally gets poorer gas mileage, but is often a much nicer vehicle for the price of the econobox that I reserved. Last summer, I ended up with a Saturn Outlook (same as a GMC Acadia or Chevrolet Traverse) for the price of something like a Toyota Yaris. I didn't exactly need the AWD in Michigan in July, but the gas mileage was just fine compared to my 3/4 ton Silverado. My father and his lady companion quite enjoyed the roomy leather back seat while we meandered around the northern lower peninsula.
Of course, there's no guarantee you'll get something with AWD, but the rental price for SUVs tends to be high, so they're often left over. On a previous occasion in Spokane, my crackerbox reservation got me a choice of a Nissan Maxima or a Jeep Grand Cherokee. Again, it was summer, so I took the Maxima.
You also run the risk of getting stuck with whatever you actually reserved (the two-door Ford Festiva with a 3-speed automatic) or maybe a pickup truck (hey, the kids can ride in the bed
- who's paying for this, anyway?).