3BOSH

Audis here in Saudi are considered not very desirable when used (except for the new A8 for some reason and Q8)
I have been looking for a luxury car that has acceptable mileage and adaptive/active cruise control that works on its own in stop and go traffic.
it appears these all are applicable to A8s from 2012+ here according to the specs
in terms of priority to try to have some sort of an order I would say it is the comfort (suspension/seats/tire & wind sound deadening & decreased Noise/vibration/harshness) then reliability, then fuel economy.
I could not find 3.0TFSI car with the radar so it is either a 4.2fsi, 4.0TFSI, or s8 (4.0TFSI w/big turbos)
This is where I ask if the s8 is actually stiffer than the a8 and if so by how much.
It appears the 4.0 is better in mpg slightly than the 4.2, and almost identical to the S8. But from reading online it seems that MPG is misleading slightly as these cars age and have carbon build up so if you guy can share real conservative driving city MPG ( i got on the websites 13.6L/100KM 4.2, 13.1L A8 4.0, 14.4L S8) not in gallons to avoid UK/US confusion.
But now reliability comes into play, I have read online that on the 4.2 the timing chain is on the front on one side and on the back on the other so it is an engine out job.
PCV, coils, sparks I have read and watched everything I can find on the engine and the car itself so I am ok with consumables. I just don't want a major engine job or a catastrophic failure (unless I can inspect for it easily before purchase by myself or a garage)
like for most common jobs for the 4.2 and 4.0 like PCV's, oil coolers, oil\air\fuel separators, water pumps, and fuel pumps. Are any of these an engine out or as extensive of a job on either V8s? where is the timing chain on the 4.0 (hopefully at the front being just a pumper and some parts off job)
from my basic understanding it appears if you just buy a running 4.0 and reroute/delete the oil screen and change the PCV u basically have a breakdown free maintenance only engine?
w12 horrible mpg in the city, and has 4 more sparks and coils and worst of all if it is like the Bentley then it is almost engine out for everything.
side note: any advice on inspecting certain items is appreciated, I am not that familiar with turbos and Quattros & their maintenance as I am come from basic v6/v8 N/A cars but I got decent learning from past experiences and the internet obviously. We usually do not change the fluid if a car is past 150k KM if the transmission fluid was never changed.
Is higher mileages something to be worried of I test drove and inspected a 2012 300k km car that had recent maintenance it was honestly better and smoother than my 100k and 150k cars, it however had a slight rattle that could be a chain from cold start (left only for 1 day) but stayed for only 1 second. What I am asking is when should I need to change timing chains preventively and are high mileage rattles ok on cold? can't wait for the replies, no a8 diesel/electric/hybrid as far as I know ever came here. Wtf is a 50 or a 5.0 engine I find one car but nothing on wikipedia & youtube might be a 6 cylinder diesel.
Thank you.
Hopefully becomes a new concise buyers guide

Striker2237

The W12 is the most reliable by far and easiest to work on for any issues that may occur.

The 4.0 has a lot more issues overall but is relatively easy to work on......

The sport suspension in my experience is softer when set to comfort and harder in dynamic than normal suspension as I have a car with sport and a car with normal. Sport also drops lower by default but the shocks cost over 2x as much

3BOSH

by sport suspension you mean the S8's standard one, or is it an option for A8?
I found an insase deal on a 2013 A8 w/ 4.0. 2nd owner very good exterior and interior condition with 200k km(125k miles)
I will inspect it drive it and take it for a ppi but I would appreciate any advice on anything major to avoid going wrong before purchase
then I would appreciate advise on tackling stuff preventitavely like removing oil screens or rerouting them w/JH motorosport kit.

Striker2237

The S8 and most W12s have the sport suspension by default with the S8 always having the TVD and adaptive steering, these items when combined VASTLY alter how the car drives when pushed hard for the better IMO.

All other A8s have sport items as options except for the 4.2 TDI that is also a S8 type car by default as far as I know.....

As far as the oil screen goes I would just remove it and/or use good oil on time. It's one of the major issues with the other being the typical cooling system leaks, those are not hard to deal with since nearly everything is located at the drivers front corner of the car accessed from below.

2turbos4rings

That would be the Audi quattro with Sport Diff, good sir..

You recently missed out on this beauty in Qatar

A very lovely W12

dxviddc

A dozen people sent me this car and I think I said something audibly out loud when I first clicked on the link. If it was in the states I would be applying to every local credit union possible for that thing.