I am thinking of using priceline to rent a car for a hiking trip.
The problem is, there are some pretty rugged roads out to the
trailhead, so I pretty much need an SUV (NOT necessarily a
4WD one).

I'm wondering what sort of guarantee priceline gives as far
as class of car. With a rental through the rental-car company,
you can just walk away if you do not like the car they want
to give you. Not so with priceline, since you've prepaid.
OTOH, maybe since you've prepaid, they really do reserve
the kind of car you bid on for you. (With regular rentals I've
all too often had the experience that they don't have what I
rented, and they give me a more expensive car for the same
price, after trying to get me to buy an upgrade that they know
they're going to have to give me for free anyhow).

Any thoughts on how to deal with this situation ? Basically,
I NEED to be assured that I'll get a high-clearance vehicle, and
I want to pay as little as possible (duh). Thanks.