NoahWeb

Greetings all! As the Dieselgate shenanigans come to a close (I hope tomorrow), we are considering a used 2012/2013 A8L W12. I have read most of the D4, and some D3, Self-Study Programs specific to the W12, but am looking for real-world input. For a Pre-Purchase Inspection, there seems to be consensus on the Control Arms, trunk lid mechanics and ensuring a complete service history is available. Real-world fuel mileage (beyond the standard abysmal comments)?

One area that I can't find much information on is Carbon Build-up. Coming from an RS4, I am well experienced in this. Given that the 6.3L W12 is FSI there is no fuel spray washing/cleaning the intake valves, likely leading to the same problem set. That said, the SSP's give great detail on a more robust air/oil separation process than which the 4.2L FSI engine had. Bottom line, should I be concerned about Carbon Build-Up?

We'll be using an A8L to move around our two kiddos (3 yr and 5 week old), generally road-trips and in-town driving. Being stationed in Japan presently means no test-drives sadly until we PCS back state-side. Any other inputs would be appreciated!

MP4.2+6.0

Welcome. I don't think anyone on the board has a D4 W12. I had the D3 W12 for almost 10 years and 100K so always like them and their exotic uniqueness in a production vehicle. Looked for them in D4 decision, but never found one to my spec--starting with less common five seater after tiring of 4 seater w/ D3.

D4, control arms continuing from D3, yes. Also sway bar links. Haven't heard anything on D4 trunk mechanics; it was always a D3 issue, and still is on an ongoing basis many years later. On D4 and especially pre-facelift, it is simply the sub par trunk size often discussed.

Carbon build up. Honestly, RS4 motor was probably one of the ground zero's, as was 3.2. There haven't been any W12 motor posts for D4 I recall, so it would be a TBD. But given oil separation already implemented on D3 W12, I sort of doubt it. The oft problem was the under designed PCV system as motors transitioned from port to direct injection. If they dumped the oil vapors via PCV right into intake that typically have a lot of water condensation, bad recipe for fouling. Anyway, no info I know of on D4 W12 about it, but oil separation design should handle it. Basically everybody here with a D4 has an FSI system on whatever motor, and just not a typical post topic--again light years different than RS4 or 3.2's in various applications. Only cross over here would be the early use of 3.2 for D4's in Europe or other markets.

Jack88

Well, there was one poster who had a W12 a while back, but I haven't seen him around. I understand the challenges of buying a car overseas, I've done it on two separate deployments. Always an interesting proposition. I can promise you could not be disappointed by an A8, W12 or otherwise. A lot of people will point out the 4.0t would offer more performance and better fuel economy, but the W12 will typically be appointed with nearly every option available and does offer a special character, something about the way a 12 cylinder delivers power. I haven't driven a W12, but if it's anything like the 12 pot I put around in now, it's truly a singularly unique way to accelerate. Buttery smooth and unceasing torque. No head snap, though, more like a force of gravity pulling you into your seat.

MP4.2+6.0

Welcome. As a D3 W12 owner, always a great and unique ride. Lower volumes for D4 than even D3 W12.

On tuning, no real knowledge on any players. I see MTM does not have a tune or mod for ECU, which they did for D3. Tiny player in North America and support very limited. ABT doesn't seem to support it either. If you find it anywhere, probably a German based tuner. W12 uses twinned ECU's, which makes any reflash modding harder at margin. But practical issue is probably too little volume to support it, and every year more higher volume markets for tuners to go after with so many turbo'ed factory motors now.

Not sure on theoretical top speed. It will be less than the Bentley W12's since it isn't turbo'ed like they are.

MP4.2+6.0

Mine was 2006 A8L W12, BSB motor at 450HP rated stock.

I'm skeptical that there are any real gains, as I always am with a normally aspirated well designed flagship factory motor. My view is if the factory could find it and it believed it was reliable, it would do it. The motor for D4 remained similar to D3, except now FSI and another 0.3L of displacement. They have had >10 years of thinking on the motor as of the D4 intro, and that D4 one is the third major revision. Primary remaining power is blown, which is where Bentley was in same era as D4. Where D5 will be (and back to 6.0L) if they release the next W12 motor they have already shown and is probably similar to the one shipping in the Bentagya w/ Conti to come. No idea on any tuners, and if he/they are talking ECU tunes, they have to deal with the twinned ECU's. Design requires both be flashed at one I think, since they talk to each other. If disconnected from car, it might be possible serially. I'm not a believer in the K&N type filter stuff either, which on an NA motor longer term I think is performance subtract if it fouls the MAF's. Hard to believe the twinned airboxes with very straight in air feed aren't already up to it, esp. with later normally aspirated 4.2's doing 350HP or so with a single box. To me, ultimately the upgrade was...S8...especially since as empty nester the limo back seat was no longer a driver for me.

Volume for D4 is almost none in USA. Peak was in the many hundreds for D3 for USA, and then came back down to a few hundred. Not sure they even cracked 100 for USA w/ D4, other than maybe first year or so. I have yet to see one in the wild, while when D3 was still the current model, I would one maybe monthly, including several near me. Tesla has pretty much taken over the high end luxobarge market here in NorCal. If you e mail with Audi USA customer relations and are persistent, you can get the production numbers from them for USA. It is truly an exotic. Lower than R8, which is (was) high hundreds annually.

MP4.2+6.0

Search archives for next W12 info. I posted it a few years ago now IIRC. Audi showed it. It was back to a 6.0L, now blown. Basically just look at a Bentayga or a new Continental for more or less the specs.

Audi doesn't have a V12 gas, so dealer is mistaken. There was a V12 diesel IIRC, but chances of that coming here are even lower than the now former German CEO of Audi escaping his Deutsche kooler cell while awaiting charges or trial for TDI gate witness tampering in the Vaterland.

No known tuner, and again I think you are imagining illusory gains. It's normally aspirated and factory already got what they could. Even w FSI and 5% more displacement on D4, they only moved it 50HP off the already carefully designed 450 HP D3 W12 motor. If you look, MTM supported a D3 ECU mod. But all they claimed was governor removal and NO h.p. or torque increase. They are one of the handful of Euro native tuner who focus on Audi, so if they couldn't get any, that's another clue. Exhaust is already quaded out too coming off the manifolds and it is twinned air boxed, so probably little there either beyond maybe some high flow full custom cat stuff.

There certainly are 4 door L 4.0T's with the Barcalounger option. So, yes you can basically get to a W12 type interior and the extended wheel base with the 4.0T and then tune it with APR or other choices. Those with the Barcalounger seat set up are more likely to have full leather too, and maybe the Audi Exclusive interiors. When you combine it all, you can basically replicate a D4 W12 for all the other goodies. You couldn't really do that on the D3 W12 for some of the nuances for a USA spec one. Hidden, but W12 is also geared higher for fuel economy. Thus, even ignoring the slightly greater W!2 weight even with the other car fully optioned up, you can also get better off the line with virtually any other gas motor if tuned to similar HP and torque.