navin in KC

I have a 2005 A8L with a 4.2L engine. I would like to know how the acceleration and driving would compare to the new 3.0L TDI engine. Is there also a plan for a larger TDI engine in the future? I thought I read something about that.

Seaclav

I had an '05 NWB A8, currently have a '12 4.2 NWB, and have covered maybe a hundred miles or so in a rental 3.0 TDI in Europe last month. I would very likely have bought a TDI but they're only selling them here as the L version, which I didn't really want.

To my way of thinking about acceleration, the really difference in the TDI is that it appears significantly more sluggish in very low RPMs, like when moving away from stationary, but you hit a surge of acceleration around 1500 RPM or so which does feel very rapid.
Compared to the '05 A8, on a 0-60 run, I'd expect the first 2-3 seconds to feel slow, and the remainder to feel very quick.

For normal, around town 30-50 driving, the biggest difference really will be in managing the gearbox. Felt like the TDI box was set up to be more conservative and change up earlier in the power band (which makes sense), but if you're happy to put the box in S or M modes, and keep the revs high and gear lower, you'll have plenty of power and acceleration to play with. So instead of leaving it in D, and loping along in 8th @ 1300 RPM, go to manual mode, 4th gear, 2K RPM, and drive like a hooligan.

Biggest acceleration "problem" I noticed was the initial slowness and subsequent surge when accelerating from stop made me have to adjust the following distances, as I frequently ended up much closer to the car in front while entering a freeway, or leaving a stop light, than I had intended.

There is (?was?) a 4.2 TDI in Europe. Would love to see it brought over here, particularly in NWB model, but my dealer didn't know anything about new A8 TDI models in the US when I last asked...which was maybe July.

HTH,

John

perlfather

I own a 2006 A8 4.2 and have driven an A7 TDI. The torque numbers= "acceleration" tell the truth. (about 317lb ft at 3500 RMP for the 4.2 vs. 406 at 1750RPM for the TDI. The TDI will accelerate faster especially from something like 30 to 60mph - obviously. The torque of the TDI is quite amazing and should be experienced if you have any questions. I think the turbo lag is virtually non existent - perhaps due to the turbo design. You have to try/experience it to believe it. Once you do, you'll be sold on the TDI.

navin in KC

I finally made time to drive the 3.0L TDI at the dealer yesterday and it seems similar to my car off the line, but the torque does pick up quite quickly and I'd say it overall seems like it has a good edge (better power) over the 4.2L engine in my 2005. Impressive for a car that gets quite a bit better mileage.