D2 S8 information. (Differences from A8)
 

I've learned some things about the D2 S8 since owning a 2001 that doesn't seem to be common knowledge. I thought I'd pass it on. I also have 2 A8's and 98 & 99. There are differences after 2000 I know (facelift), but I'll do the best I can to weed those out. (Gauge cluster/graphics, center console, radio, 5V heads, 3 stage intake, throttle by wire, door handles, mirror shape, fenders, hood/grille, headlights, front/rear bumper covers & trim, seat style, solar moonroof, steering wheel with controls, navigation, some control arms have a smaller ball joint than pre 2000 facelift, steering rack, center arm rests way better, door arm rest has better cushion for my elbow)

Differences from the A8 to S8 as far as I know. Please correct me if I'm in error...
Most notable difference in my opinion, is the transmission. Not the programming, the gearing. It's geared much much lower than the A8. Yeah, the horse power is slightly higher, but the engine revs much higher at same speed in same gear as an A8. Personally I think that's a bad thing, and I wish it wasn't so. I'm near certain the transmission internals are the same, but the output gearing at the rear in the gear case is most likely where the difference is. I'm thinking of swapping the transmission or gears for an A8 version. Just not sure if I can get the speedometer to read right if I do. If I can solve that, I'll swap it this winter as I have a spare tranny. The lower gearing isn't necessary. These things go like hell anyway. Why ruin the highway feel. I like having the motor tach only 2000rpm doing 70 in my A8, vs about 2800rpm in an S8 same speed. Just more wear and tear on the engine/transmission and worse gas mileage. The trade off can't be more than something like 1/4 or 1/2 of a second 0-60. :( My opinion anyway. One more thing, and I'm not positive, but my S8 has transmission shifting buttons on the steering wheel and don't don't recall seeing those on the facelift A8.

Motor is tuned different for 20 more horse power. I don't believe any engine parts are different ?

Suspension is 3/4" lower, and stiffer. Wheels bigger and tires are thinner too. If you have an A8 and change to an S8 you'll miss the ride and it'll take a while to get used to the bumpiness. especially if you live with bad roads like I do. I believe all control arms are identical to A8, though the rear sway bar is a larger diameter.

Outside visuals things like badges obviously. And mirror housings are aluminum.
Steering wheel is 3 spoke with S8 badge.
Gauge cluster is different. higher limit on the speedometer and S8 badge.

Engine may have different internals or be balanced better to rev higher. anyone know for sure ? Has a pretty high rev limit for a V8. Higher than the 98 and 99 D2s I have, but I know the motor has a different top end too like 5V heads, throttle by wire, etc that changed in 2000 for A8 & S8. Intake it 3 stage vs 2 stage. So maybe the facelift A8 has the high rev limit too ?

Massive front brakes. The rotors are about 14" diameter, and the calipers are 10" tall !!!

Exhaust has a different sound. Probably different muffler. Exhaust tips are different and polished stainless.

that's all I can think of...I love these cars !!!

Thanks, very useful. A lot of people think S8 and A8 is exactly the same except for wheels and suspension. They are quite different though if you look at all the facts. Thanks again!