really hard to beat the Skyline, regardless of price, at least for what's important to me.
If I can give up rear seats, Audi R8, with a supercharger kit. That car catches my eye more than anything else on the road. Or with a £400,000 budget, I'd take a Murcielago LP670 SV...and twin turbo it to a thousand horsepower.
But keeping a front engine/2+2 configuration, I can't think of a single thing, and I've tried. There are saloons that you can push up to silly Skyline-level power levels, but they either don't have AWD or they just can't handle like a Skyline. There's the Evo of course, but giving up displacement and two cylinders is going in the wrong direction!!
wait, there is ONE car that would work - a 911 Turbo. But it would need a lot of tuning to get it up to where I'd want it power-wise, and I strongly favor the 993 with its spartan interior, and I think 600bhp would be possible, but it is a LOT more difficult to get power out of an air-cooled engine versus a liquid-cooled engine. And I just don't think 911s are as forgiving as Skyline GT-Rs are. One day you just know they will swing around and bite you in the ass.