Does she want new? If not, a late-model Cadillac XLR might just be the ticket; I talked to a guy who had one and he says it's not as low-slung as a Corvette even though it's based on the same chassis. Either of the V8 Dodge Challengers would also work if she wouldn't mind the numb steering, though that seems to be a high priority. Jag XKR may be a bit too "old-person" for someone young at heart.
How about one of the last Pontiac G8 GXPs? Can be had in an auto, handles decently and is a very straight forward car to use. Same engine as the 'vette too.
She's 80? She looks pretty good for her age! And I wish I could be as awesome as that at her age...