German Car Zone

In my extensive experience with both the 320 CDI and 30d engines in the Mercs and Beemers respectively I can say without hesitation that the BMW engine is smoother with a more linear power delivery.

Cool's right - it doesn't give that instant slug of torque like the lower-revving Merc engine but it's the one diesel engine I've felt that revs crisply and smoothly all the way to 4500 rpm. It's the best diesel in its class and much of this is down to the fact that it's a straight six.

I equally was left unimpressed by the 3.2 TDI engine in the A6 when I gave that car a proper shakedown over a weekend.