Online Travel Booking and Bidding Agencies - Question on Car Rental thru Priceline

Howdy Y'all.

I have booked a car thru Priceline next week. Got an outstanding deal--Convertible for 18 a day. Priceline somehow screwed up the dates from Thur thru Tue rather than Thur thru Sun. But still comes out to a Convertible for $40 a day with taxes included. ( I will forfeit the last two days of course)

But my question is. . . When I arrive and they do not have a Convertible available what would be the normal Upgrade Car that I should receive instead of the Convertible. I know the Convertible is probably a Mustang or similar. But the hardtop Mustang is a much lower class car. Should I push for Premium or SUV?

Depending on the company,a convert. is often the same price as a luxury. I'd go for the luxury.
Since I've never used PL for cars,I'm not familiar with the wording in their agreement.But I would go to the rental cars web and copy their listing of car groups.