How does the D3 A8 stack up powerwise with it's competitors? Have anyone driven the other brands to give a good comparison? Since there is 2 versions of the 4.2 L (2004-2006 335hp) and (07+ 350 hp FSI engine), how fast does the two versions feel compared to:

1. BMW 745LI/ 750LI

2. Mercedes S500/ S550

3. Lexus LS 430/ LS460

Can the A8 keep up? I know these aren't race cars and speed isn't everything, but power wise specifically speaking of low range torque and midrange power for the big sedans. Contemplating which one to buy.

Thanks!

 

I had fun cat & mousing A Lexus 460 between Beaumont & Houston a few weeks ago. I have the 330 HP and could pass him at high speed acceleration from 100 to 125 no problem. HP is not everything. Gearing, final drive ratio,torque and quattro all help.

 

1. BMW 745LI/ 750LI

2. Mercedes S500/ S550

3. Lexus LS 430/ LS460

Can the A8 keep up? I know these aren't race cars and speed isn't everything, but power wise specifically speaking of low range torque and midrange power for the big sedans. Contemplating which one to buy.

Thanks![/QUOTE]

If that is the biggest factor for your decision, most definitely go with the BMW.

 

But if you want to outrun all of them at the light, especially when it is wet, than go for Quattro (4MATIC can do too ). You can't race them any other way anyways unless you want to end up in jail.

 

'Not sure how 4wd will help at higher speeds in terms of acceleration, it will have higher mechanical losses certainly. Apparently, tyres with a small amount of torque applied have a lower rolling resistance than those freewheeling, so the losses through the drivetrain are partially offset by lower rolling resistance of the front wheels.

 

I have the 745i and s4master1 is right.

 

4WD creates more mechanical loses at all speeds but gain in traction makes it superior at high acceleration only possible at low speed. At high speed aerodynamic takes over and I think A8 has better aerodynamic coefficient and probably a bit smaller cross section compared to the rest of flagships. That leaves more power for high speed acceleration (Mister Bally's experience). Gearing was designed with consumption in focus rather than acceleration. We with North America's speed limiter would hit it in fourth gear before we hit rev limiter. That makes 5th and 6th overdrive gears. With enough power and no limiter A8 would reach 350 km/h (220 mph) in 6th gear. With quite lower geared final drive(s) acceleration would be better but consumption would kill us.

Low end torque is not that important with short throw 6 gear transmission. It will downshift anyways when gas pedal is depressed and provide adequate torque on wheels. As a matter of fact, torque and power are very close connected values. Torque multiplied with rpm gives power. So speaking about high torque and high power engines is a bit misleading. When comparing engines only one of those characteristics should be used. Either: this engine has more torque at low rpm but less at high rpm than that engine, or: more power at low rpm but less at high rpm. Of course saying this is high torque engine and that is high power engine is perfectly understandable, but thinking about that in a proper way is better ground for further evaluation (if any comes ).

 

Meh, the car doesn't have a lot of low end torque period. It's a slouch right off the line and then picks up pretty quickly. The A8 is a highway cruiser in my opinion. I was rolling on the expressway last night, left it in third gear and it had plenty of power for that. It's a bit of a disappointment from a stop though.

The engine sounds beautiful though and the exhaust actually makes some noise.

 

[QUOTE=Mike_k;24172266]Meh, the car doesn't have a lot of low end torque period. It's a slouch right off the line and then picks up pretty quickly. The A8 is a highway cruiser in my opinion. I was rolling on the expressway last night, left it in third gear and it had plenty of power for that. It's a bit of a disappointment from a stop though.

totally agree.
with the exception of the Bmw all these large sedans are sofas with wheels at take off, The A8 happens to have traction in all 4 of them but makes no difference at low speed except in a few weather related conditions or maybe on unpaved roads.
other than that I actually see Quattro to be a disadvantage on a big heavy sedan, works great on smaller lighter cars thought.

 

The BMW will be faster, and feel more sporty to drive. In most races in the dry, the BMW will also win. If you want a race car, buy the BMW.

If you want the most cosseting ride, buy the Merc.

I spend most of my time in the car NOT racing - and I spend more time inside than out, so the interior really matters.

No contest - Audi for interior. And the lift mode on the suspension is surprisingly handy for strange driveways / speed bumps where BMWs would scrape.