angrypengu

I'm not sure if it's a good idea to ask for my input, but since you did, happy to oblige. I apologize ahead of time, I get rather technical here, -it is my nature. I will try to get ' to the point', and if you would like further detail backing up each point I am happy to dive in. I don't want to bore/waste anyone's time by getting too technical.

TLDR: I came from the Mercedes family. I was highly highly incentivized to buy the S class. Despite that, I chose the D5. Pls allow me to be clear. After all was said and done, the negatives of the S class far outweighed the price incentives so when it came to decision time, it was a rather easy decision to buy the D5. Both vehicles are amazing cars, but based on what I was looking for, it was a no brainer.

Engine Mechanics/Reliability: There is no doubt the present model S class (W222) has a tried and tested motor. (Model 2019 and before). The present S class is the last year before they too go mild hybrid (and on the S450 to the inline 6 motor). I expect the 2020 models to be similar to the D5 in engine design. This was a main "advantage" to the S class because as you all know by now, I am against the 48V system due to longevity concerns. That said, Mercedes proudly totes in their technical documentation that the M276 engine (used on the S450 and S550 in V6 and V8 forms) has a LOT of plastic parts in it in order to save "weight", so they say. I've worked extensively on the M272 engine and one advantage to that has been solid build quality. The fact that MB cheaped out on the M276 engine was the first of many straws that upsetted me. That said, it is clear to me that the M276 engine does not suffer from any major engine issues and does not suffer from the dreaded carbon buildup issue that most direct injection engines face. The M276 engine also allows for cheaper maintenance if doing this yourself as it simply calls for MB's 229.5 oil and the legendary M1 0W40 oil is cheap and oil changes on MB vehicles are easy. That said, I recognize most people don't do their own oil changes, and Audi made this easier for me as they included Audi Care...

The EA839 engine on the Audi A8 with the 48V system did initially scare me from a reliability perspective. However, said engine has been on the B9 S4 for two years in NA, and is on every single major Audi and Porsche model either now or in the future (cue Cayenne, Panamera, A6, A7, a8, etc). This is the first of many limited models of engines that carmakers are making due to WLTP concerns (emissions). If there's anything systemically wrong with these engines they will seriously affect VAG/Porsche so I'm confident that they've done their homework this time. They've also hopefully learned from the turbo failures in the 4.0T D4, and like all Audi engines as of late, they have a pretty good air oil separator so on the carbon buildup side of things, we should be OK. I have been checking the PCV system on the D5 and I do see oil in the tracks, but between PEA in fuel and the new 508.00 oil standard, I believe (no facts yet) that this should be OK once it reaches steady state accumulation on the intake valves. If we did have issues, I would have started to see CEL or other complaints on the B9 S4 forum and nothing yet.

TLDR: The S class (2019) model has a more proven engine design without any major issues, and the D5 A8 is basically all new, but given the fact it's been in the market (this engine) in other applications and will continue to be a major engine in the VAG family, this risk, I believe, is mitigated somewhat.

Comfort/Build quality:

I am woefully disappointed by the W222's build quality. Post FL, several parts that were metal have become plastic. Almost everywhere I touch (ashtray area anyone?) on the S class is plasticy. The windshield stalk is flimsy, the buttons are flimsy. Also in NA, for the S, you have to buy the exclusive package to get the extended leather interior (and the wood trim in the door, below the armrest) and the exclusive package forces you to buy the premium rear seating package which is a waste of money for me. When I tap the doors on the inside, it just feels and sounds hollow and cheap. This extends elsewhere. On the S class, there is no headlight washer jet - they cheaped out on running the lines for that feature and there are a myriad of other example of just that here - most people wouldn't know, but I do. The S class's wiper's blades are hopefully overdesigned so it's like $250 for a set of blades! I get what they were trying to do - the D5 implementation is much better here. The HUD on the S is known to be squeaky and thus requires customers to put in felt (seriously?). The Burmester Advanced 3D sound system (the 26 speaker version) is absolutely mindblowing, and I do believe is better than the D5's B&O 23 speaker advanced 3D sound system. If you don't get the sound system upgrade on the S, it sounds absolutely woeful and befitting on a Civic. There's not even a subwoofer on the base Burmester sound system!!!! (ridiculous!!). The massage seats on the S class are hopeless and a waste of time, but above all else, these two things turned me off of the S class, and quick.

1) The steering wheel is not perfectly aligned in the center of the driver's sitting position. This has been a hallmark feature of many Mercedes models. If you sit straight in the driver's seat, and you arrange your arms straight forward, you'll see the steering wheel is offset (google "Mercedes steering wheel offset" for photos). Driving in a contorted position is absolutely not acceptable for me, and is something that has been bothering me for a LONG time in my Mercedes cars over the years.

2) The Premium package on the S class gives you the enhanced seats/leather, and it really bothers my back. I can't explain it well, but when I sat in the S, it gave my back the same feeling as if I'm sitting in a regular chair while touching my toes with my hands. It pulls on my lower back, and it really bothers me. After pointing this out to a few friends in my firm, they noticed the same thing. There's this abnormal pressure, and since the massage seats suck, well, that was what sealed the deal and pushed me towards the D5. It is clear, to me, that the S class seats are meant for the 'larger' gentlemen. Even fully adjusted from a bolsters perspective, the seat just didn't accommodate me. I felt like a child sitting in those seats. Unsupported, etc.

Ride/Noise/RUN FLAT TIRES (grr!)

1) The S class is nearly as quiet as the D5, but not as quiet. Car and Driver's instrumented test proved that, and my own testing with both cars on the same road/weather/speed using an ANSI calibrated (weighted A) decimeter revealed the same. The D5 is the quietest production car that money can buy, beating the Maybach in 3 of the 4 categories tested by C&D. The only portion where the D5 lost out was idle noise with the Maybach beating it by 1DB, but who cares? At speed though, the D5 is a few DB quieter than the S, which is surprising.

2) The S class does not have a spare tire and has run flat tires which causes the ride to be rougher, especially over speed bumps and pot holes. The air springs simply cannot counter the jarriness of the run flat tires. Yes, you can swap out all tires but money can't solve the issue of what happens if you get a flat. The only other option is to carry a spare tire (from the W221 - the older S class) which is a donut, and you put that in the trunk. Not only is this unsightly, but it seriously kills trunk space, which on the S is already lacking - and if you get the advanced sound system upgrade, the trunk is even smaller due to the placement of a subwoofer.

3) The S class has staggered wheels - which makes tire rotations un-doable. I've seen the consequences of this first hand, and while not a show stopper, it did tip the scales towards the D5.

TLDR: If ride quality/noise comfort is something you care about, the D5 wins, by a pretty large margin if you take into account the RFT issue.

Everything else:

The S class has more presence, without a doubt. However, I prefer the incognito-ness of the D5, and the fact that basically no one has one. I also buy cars for me, not for others, so on this point I didn't really care. The infotainment system on the S class is nicer in some ways (no need to clean the screen a bunch of times) but then again it's getting pretty dated. I would say preference for the MMI/Comand is a subjective thing. Knowing what I know now, I prefer the MMI's layout but I don't like the fact that it gets dirty quicker. Perhaps the main thing that I dislike about the D5 is the stupid black trim which does scratch rather easily. I do believe I've found the best way to fix it, and am working on honing the details down and then I will post what product to use and how on this forum. If I do nail that process down, I think I'll be OK with the piano black wood, later.

TLDR: The S class is a 'safer' choice because it's been around much longer, and is a more showy car. I do miss the three pointed star on my hood though....! However, for the things that matter to me (ride, comfort, build quality), the D5 wins. I have mitigated the risks in the D5 by learning about everything I possibly can and then making a calculated decision to see if I have appetite for it. All in all, I am comfortable with the risks of the D5, and I know the financial implications of these risks. I also have gone through the extended warranty terms and conditions on both cars. Between the financials and the legal terms which dictate what is, and more importantly, what is not covered (mild hybrid battery and air springs, for example), I feel I know enough of what I am getting into.

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Hope that helps! If there's anything specific you would like more info on, or have any other questions for me, I'm more than happy to share :-) The S class, and the LS500 were the two main cars I compared against the D5 A8.

PS After reading this again, I worry that I wrote too much. (sorry). There's a LOT I left out, so happy to talk about other differences. Some of which I have no doubt may make some people's eyes roll