Its also just the power delivery is all wrong. Diesels excel at low-mid range power, which makes them excellent road cars, as what power they do have is accessible from low RPM's and makes the car feel much perkier than its peak power figure would suggest. On track however you spend almost all your time at high rpms, where diesels tend to feel a bit rubbish (partly because of the small turbo used to give good low-mid characteristics, and partly because diesels just dont breathe that well and dont really like to rev).
Furthermore, because they make so little power, they're all turbocharged from the factory, which initially seems beneficial but has its issues. What i mean by that, is if you have a naturally aspritated 2.0 petrol, it'll easily make 150hp and some factory engines are exceeding 180hp. A turbocharged one will thus easily reach 300-350 with a sensibly sized turbo and non-silly boost pressures, and thus will still drive pretty nicely. A naturally aspirated 2.0 diesel however will make about 70hp, and thus a turbocharged one ends up in the 150hp range while still driving acceptably. If you try to get to 350 in a 2.0 diesel, its sorta like trying to get to 600 in a petrol, and lots of compromises appear.
They also lack throttle response. Even turbo petrols can suffer a bit in this respect. I spent years driving turbo petrols, my current road car A4 1.8T has 280hp, but i recently had a shot of a Clio 172, and while clearly slower than the A4, the throttle response and crispness of how it delivered that power was stunning. I've since driven my dads 4.2 V8 S4, and it too has excellent throttle response compared to the turbo petrol, which is exactly why i'm now part way thru removing the 1.8T from my track car, and fitting a 4.2 V8 instead.
It sounds like a fairly new car thats probably worth a bit of cash. I would be very surprised if you couldnt sell it, and use the cash to buy something much more "fun" both as a weekend road-car and a track toy.
