Originally Posted by kc1337
No idea, modding potential on the diesel platform is very limited right now.
I agree because there are not too many products out there, YET!
I disagree because the diesels have a massive potential for tuning. ...and unlike gasolene engines, the more you tune and improve performance, the more efficient they become.
Your first mod should be an upgraded intercooler. The colder the air for your engine, the thicker it is. The thicker the air, the more oxygen per unit volume of air. This is VERY important for improving the burn of the diesel considering that diesel fuel continues to be injected in the combustion chamber during the piston down stroke, long after ignition has occurred.
Obviously the next mod should be a engine tune or software reflash. For the time being, you might be better off searching for such a mod in Europe where diesel is king! I guarantee you there are companies out there that specialize in tuning diesel engines.
The 1.9TDI engine in the VWs is a fantastic little engine. Stock it comes with 95-110 hp depending on the model year and it gives you about 35-38 mpg combined city and highway driving on the VAG A4 platform. Fully modded this thing has more torque than a Dodge Ram truck. Some users modded their engines in such a way that they get about 72mpg with VERY VERY careful driving.
So yeah, the diesel platform has a lot of potential! It has been highly underestimated BY FAR.