I am pretty sure no, but....... my GM card now allows you to take a $50.00 cash payment for each $50.00 in value you have. So........ if yours is the same as mine, yes you could get the value on your card in cash and use on a used vehicle or whatever you wanted to spend it on. There are two types of GM cards now (I believe), the old GM card which I have, and the newer style.
I have the older card and you get 5% of all purchses toward a new GM car up to $500 per year and a max of $3500. I have saved over $3000 on new cars with it. It is used after you get your best deal and counts just the same as cash. I never keep a balance so could care less about interest rate. Gmcard has been very good to deal with. Had card number stolen a few years back and thay "forgave" over $15000 in stolen charges with no problems.
Recently worked for Cadillac. GM points are only for new vehicle purchases and there's a limit despite your total earnings how much you can use depending on which type of vehicle. It is used as cash off the total bottom line. If you're consider new, call the dealer and they can tell you how much of your earnings you can use.