turbo or not
I have had the W124 300D and now have the W210 E330TD. The first was built far better and rust on the W210....lets not go there. The 300D was slow, I would guess 0-60 in about 15 seconds on a good day, and gave about 25-35mpg at best. It would have gone on forever. Previous posts are right about the turbo not fitting in RHD cars. The W210 E300TD turbo and exhaust system is BIG.
I did consider tuning the 300D to get more power but frankly it wasn't worth the money. The engine was designed for 500k miles not 0-60 blasts.
The E300TD would respond to tuning very well. 212hp is possible out of these with huge jump in gearbox ripping torque - 385Nm. But again - is it worth it? Buying diesel is surely all about fuel consumption and longevity (as the bodywork rots away
). Sure, the torque is fun, but with an autobox one needs to wait a second for it to work out you need to move ASAP.
I have to say two performance hikes stand out that totally blow me away. The first is for the W211 E320CDI. It is possible to reliably get 243hp and 550Nm out of the engine. Sh*te!
But for the monster W211 E400CDI - get ready for this - the same company can extract RELIABLY 311hp and 600Nm of torque out of the engine!
Wow. What would 600Nm feel like? I think ASR would cut in in 6th gear on a summer day with that!
I wonder what is possible if reliability is reduced? One gearbox a drag I would reckon!
Still, I bet it would be tempting to use this power and with that goes your MPG.
For more info for those boy racers out there
see:
http://www.torquingbhp.co.uk/pages/dieselturbo.htm
http://tunemytdi.com/html/contact.html
Power steering box is in the way on RHD models so MB didn't bother for us brits. 
