Triumph Spitfire 1500: Not much quicker than a Nissan Micra in a straight line, but it's an eager little car that likes to kick it's tail out now and again. Agile little thing that was made for narrow, twisting routes like Britain's country roads... or Costa Di Amalfi.
Ford Ka 1.3: Only 60BHP coming from it's ancient engine, but it's fun on twistier bits of tarmac, such as Motorland, Amalfi, certain bits of the 'Ring, etc. I think it does a better job of being a modern-day Mini than BMW's effort!
Honda CRX VTEC EF8: Loves to have it's nuts revved-off and corners well too. Feels better than the 160ish BHP you have on offer. Lots of fun just about anywhere.
Honda NSX: I'm not to to name specific models, though the 3.2 is obviously the better car. Great engine noise, and it corners very well, even if it gets a tad twitchy at times.
Lotus Esprit Turbo HC: Not the quickest one, but don't underestimate 1980s handling! Easy car to get sideways.
RUF BTR/CTR: Fun to hot-lap because of the challenge involved. YOu have to adapt your driving style substntially just to stay on course.
Spoon S2000 Road Car: Corners like it's on rails. Surely a good car for the Nurburgring 4hr.
Cusco Advan Subaru Impreza JGTC: Not the most pwoerful race-car, but good in it's own right.
BMW M3 GTR Race Car: Stable, quick, grippy. Will do the Nurburgring 24hr well, and if you just want to drive around a track very quickly for a bit, it's good for that too.
I could name a few others that I like hot-lapping when bored (Mitsubish Evo VIII, Toyota MR2 AW11, etc). These being cars I've picked because they're responsive, grippy and/or chuckable, which suits the way I like to drive when I want to have a bit of fun.