I already am living well beyond my means driving my silver '99 Dodge Viper RT/10. That's probably the closest thing to a dream car I'll have for quite a while and I'm happy with that.
If money were no object.. I dunno... Lamborghini Murcielago Roadster is near the top of my list. Saleen S7 would be nice. Jaguar XJ220. Ferrari F40 or Enzo. Maybe one of Heffner's Viper SRT-10s that put down 1900 horsepower and are still street legal and driveable at lower speeds. or that replica Mach 5 (Speed Racer's car) they sold on eBay that actually had 500+ hp, hydraulics to allow it to make jumps and working saw blades under the front the of the car... that'd be sweet. But I've always wanted a Lamborghini.