[sovietjet]

Greetings!

I owned a 2008 M3 coupe for 8 years and recently sold it. I'm in the market for a new car although not in a big rush so I'm just taking some time to research. I'm looking for something bigger, 4 door, and more practical than the M3. Currently, I'm driving maybe once a week due to the fact that there is nowhere to go, and covid has forced me to work from home. Even when I was going to work and driving all the time I was only putting about 8k miles a year on my M3, and that included several road trips.

So, initially I was looking into a used 2018 Audi S5 Sportback. Lately I've been thinking if I really should shell out $45k+ for a car when I don't drive that much. After lowering my price point I've come to the realization that there are three cars which I'm interested in.

2015/2016 550i xdrive
2015/2016 650i xdrive
2017 A6 3.0T Competition

I realize the A6 might not be popular on a BMW forum but it grabs my attention. Also I know the A6 is in a lower category than the 550/650, and the S6/S7 more closely matches them but the S6 blowing turbos left and right for me is a deal breaker. So I have the following questions:

1) 550i or 650i, what are the differences besides the obvious configuration? I understand the engine is the same, what about the suspension, interior and technology? Are there any serious specific issues to the 550i or 650i that would sway me away from one or the other?

2) Is the N63TU engine in the 2015/2016 550/650 now reliable enough? The cars I'm looking at have 45-50k miles on them. I'd be looking to drive the car at least 5 years and would like to have some decent reliability. Is it considered more reliable and cheaper to maintain than the S65 in my 08 M3?

3) If anyone else has drive all three, which feels "sportier"? Coming from an M3, I still want to have some fun every now and then.

4) If I go check out a 550 or 650, what should I physically inspect or look for to identify common issues?

5) Might be a long shot here, but what are some of the pros/cons of the A6 relative to the 2015/2016 550/650? Is the interior/tech in the A6 better or worse?

I didn't want to post this again in the 6 series forum, so I'm just hoping people here have experience with both

[walmark]

I'll share some thoughts, although they should not be taken as anything beyond my personal opinion.

- 550/650 are going to have much more power than A6 3.0T. As you point out, this is not the S6.

- 550/650 share the same power train and, for the most part, the same options. N63tu is more reliable than the original N63 and should also be more reliable than S65. It is not bulletproof though. If you want reliability you should really look at 535 with N55. 650 will be more "upscale" while 550 is supposed to be more "utilitarian", and the price will reflect that. Performance wise they will be very similar.

- "Sportiness" will depend on options. RWD are more sporty than X-drive (better steering and handling) but X-drive are faster from the line (more grip). The type of suspension options and transmission programming will also define how sporty they are. I suspect none of the 3 cars you're evaluating will feel anything like the M3.

- The material quality is roughly the same between all 3 (650 might have nicer leather options as it was meant as "upscale"). I think Audi has better Virtual cockpit than the BMW 6wb cluster, and (depending on options) Audi B&O high end sound is better than BMW B&O option. In lower tier BMW Harman Kardon will be better than Audi base sound. I also think that BMW ACC (adaptive cruise) is much more subtle and more predictable than Audi. The rest is ergonomics and really a matter of preference.

I think you're not comparing apples-to-apples here. 550/650 will be much faster than A6. But in terms of comfort and luxury, depending on options, 650 would win with 550 being on par with A6.

[Unspec]

Originally Posted by walmark

I'll share some thoughts, although they should not be taken as anything beyond my personal opinion.

- 550/650 are going to have much more power than A6 3.0T. As you point out, this is not the S6.

- 550/650 share the same power train and, for the most part, the same options. N63tu is more reliable than the original N63 and should also be more reliable than S65. It is not bulletproof though. If you want reliability you should really look at 535 with N55. 650 will be more "upscale" while 550 is supposed to be more "utilitarian", and the price will reflect that. Performance wise they will be very similar.

- "Sportiness" will depend on options. RWD are more sporty than X-drive (better steering and handling) but X-drive are faster from the line (more grip). The type of suspension options and transmission programming will also define how sporty they are. I suspect none of the 3 cars you're evaluating will feel anything like the M3.

- The material quality is roughly the same between all 3 (650 might have nicer leather options as it was meant as "upscale"). I think Audi has better Virtual cockpit than the BMW 6wb cluster, and (depending on options) Audi B&O high end sound is better than BMW B&O option. In lower tier BMW Harman Kardon will be better than Audi base sound. I also think that BMW ACC (adaptive cruise) is much more subtle and more predictable than Audi. The rest is ergonomics and really a matter of preference.

I think you're not comparing apples-to-apples here. 550/650 will be much faster than A6. But in terms of comfort and luxury, depending on options, 650 would win with 550 being on par with A6.

Something to add about the xDrive part: In this generation, the xDrive cars have hydraulic power steering (sans the 4 bangers), while RWD ones have electronic power steering. I know a lot of people who seriously prefer hydraulic steering over EPS, so it might be an important factor.

[sovietjet]

Thanks for these replies!

Originally Posted by Unspec

Something to add about the xDrive part: In this generation, the xDrive cars have hydraulic power steering (sans the 4 bangers), while RWD ones have electronic power steering. I know a lot of people who seriously prefer hydraulic steering over EPS, so it might be an important factor.

This is good to know. I think then a 2015/2016 550i xdrive is what I would want.

[spielnicht]

When I was in the market 3 years ago to replace my C350, I thought I had my mind made up on the A6 (2016 CPO at that time). Test drove it and thought it had good power and handling balance compared to my MB. I then made the mistake of test driving an S6 and couldn't even consider the A6 at the point. I remember telling myself if I can't get the S6 then I'd rather just keep my C350 for a bit longer because I didn't feel like I was getting much of an upgrade for the money I'd be spending.

I finally found an S6 200 miles away that I was ready to drive up and buy before a friend with an M3 that I've test driven before suggested I check out the M5. The price difference for same model year was well beyond my budget, so it was an immediate no. One thing led to another and I ended up at a BMW dealer looking at the 550i. From that point I was TORN for days between the S6 and the 550i, each with their pros and cons. S6 is far more sporty with killer handling and stock exhaust. On the other hand, 550i has more HP and torque (even though S6 has an insane torque band compared to 550i), and looks much better on the inside and outside (look of BMWs age better than Audis and MBs - personal opinion).

Moral of the story, don't get the A6 - it's beautiful, but slow and boring, and you'll hate your life replacing pealing interior parts. If you can't afford an S6, def. go for the 550i, or better yet the 650i since it has better handling and better stock exhaust, especially if you don't need the 3rd seat in the back, not to mention more unique on the road compared to how many 5 series you see everyday.

[Surly73]

Originally Posted by sovietjet

Thanks for these replies!



This is good to know. I think then a 2015/2016 550i xdrive is what I would want.

It's good to be aware of the differences, but IMO you need to drive them to determine if it matters to you. Shopping based on specs won't necessarily make you happy. EPS can be very good. LCI F10s are apparently a lot better. You can only tell what's OK for you and what isn't by driving them.

(Overall the driving dynamics in the F10 are really poor if you've experienced older German cars)

[sovietjet]

Yes, I will most definitely be driving them all but it already seems like the A6 is in third place for me. Last year, when I initially thought of selling the M3, I went and drove a couple of S6 and one 550i. However I need to refresh my memory by driving a 550i again. I only remember that I liked the S6 a bit more. But, they seem to have pretty common issues with turbos blowing up (there is even a poll on one Audi forum along the lines of "have your turbos blown yet?). I will definitely take a look at the 650i.

[OnlyGerman]

Audi = Trash

[Bbb34]

Originally Posted by Surly73

It's good to be aware of the differences, but IMO you need to drive them to determine if it matters to you. Shopping based on specs won't necessarily make you happy. EPS can be very good. LCI F10s are apparently a lot better. You can only tell what's OK for you and what isn't by driving them.

(Overall the driving dynamics in the F10 are really poor if you've experienced older German cars)

+1 on this advice.

Can't go wrong with either one, all are great, and neither is "horribly" sporty, especially if you go xDrive with F10.
Depends on what you expect from these. In my opinion neither is going to be anywhere close to what you drive now in terms of "fun to drive" factor.

I've taken my friend's 335 M sport out several times (2007/8 or 9 can't recall) and handling and steering feel (ESPECIALLY steering feel) of those is - well completely different from modern 3 series, not to mention 5 series or A6, not comparable really.

[Unspec]

If I remember correctly, the turbos on the S6/7 like the blow because of the turbo oil screen.

[UFTW]

Originally Posted by Unspec

If I remember correctly, the turbos on the S6/7 like the blow because of the turbo oil screen.

Yes the S6/S7/RS7 have all of the same problems regarding turbo screens.

[ezaircon4jc]

Originally Posted by Unspec

If I remember correctly, the turbos on the S6/7 like the blow because of the turbo oil screen.

Originally Posted by UFTW

Yes the S6/S7/RS7 have all of the same problems regarding turbo screens.

YouTuber Rich Rebuilds left the screens out on his RS7...

[Unspec]

Originally Posted by ezaircon4jc

YouTuber Rich Rebuilds left the screens out on his RS7...

I was under the impression the piece itself is also a gasket, so I assumed he just poked the screen out and only installed the gasket part of it.

[itzjoker]

I've owned a B6 S4 for 5 years, sold that and got a 2016 X6.
Then rented a 2016 Audi S6 for a couple days on vacation before I purchased my 2013 650i Gran Coupe M-Sport (73k miles now) later that year (November 2019). I'll share everything I've learned since owning this vehicle.

Originally Posted by sovietjet

1) 550i or 650i, what are the differences besides the obvious configuration? I understand the engine is the same, what about the suspension, interior and technology? Are there any serious specific issues to the 550i or 650i that would sway me away from one or the other?

I have never driven/been inside a F10 550xi but have in a F10 M5. Technology should be nearly the same. General appearances should look similar but imo the 650i will have some added details/touch for more luxury. You will feel like a boss in the 6 series with how the cockpit is longer. Back seats of my GC is tight but enough for majority of people. I've had many compliments about how surprisingly comfortable the back is. 550i here will probably have a bit more space in the back seats. Trunk space in 6GC is great. No specific issues to sway you one over the other as majority of any issues are engine related.

2) Is the N63TU engine in the 2015/2016 550/650 now reliable enough? The cars I'm looking at have 45-50k miles on them. I'd be looking to drive the car at least 5 years and would like to have some decent reliability. Is it considered more reliable and cheaper to maintain than the S65 in my 08 M3?

I cannot speak for the S65 M3 in terms of reliability.
Obviously the N63TU is much more reliable than the N63. I have put about 5k miles after ~1 year of ownership. So far no expensive repairs. Car runs great. Find one that hasn't been abused and get a PPI.

3) If anyone else has drive all three, which feels "sportier"? Coming from an M3, I still want to have some fun every now and then.

Comparing the S6 to 650i. The S6 steering feels lighter, which gave me the impression that the car was more nimble. Acceleration felt very linear but everything about the S6 felt very dull and muted. The 650i steering feels very solid. You definitely feel the weight of the car more than the S6 but overall car feels much sturdier. The 650i plants when you get on it (RWD). Overall with the 650i you feel much more in tune with the car rather than the muted feeling of the S6.

4) If I go check out a 550 or 650, what should I physically inspect or look for to identify common issues?

Get a PPI. Check the crankcase ventilation hoses that attach to the turbo inlet and run across the motor. Those are notorious for cracking due to excessive heat. There is extended warranty on this part depending on VIN, otherwise it's ~$300 for the part but its easy an DIY. Check the coolant lines (especially the T connector) on top of the alternator. Check the coolant lines (and T connector) underneath the drive side turbo inlet. Both those T connectors will deteriorate and start to crumble due to the excessive heat.
I have replaced both T's with brass ones in my car since they were leaky.
Both literally crumbled as I took them out.

5) Might be a long shot here, but what are some of the pros/cons of the A6 relative to the 2015/2016 550/650? Is the interior/tech in the A6 better or worse?

The interior and tech of the S6 I drove definitely had a cool factor but the quality of my 650i interior and X6 (same tech as newer 650i) tech was miles ahead of Audi. The quilted leather seats in the S6 looked awesome and soft but the quality and feel of my 650i is much higher. The S6 has a headunit that flipped out which is not my taste. The parking assist and cameras on the S6 is no where near the level and clarity of the parking assist on my X6. BMW takes the cake on this one.

Overall, the 650i beats the S6 in every category, hands down.
If the 650i is that much better than the S6 (to me), then you will be very disappointed with the A6. I may be biased here but I think the 6 series GC is one of the most beautiful cars out there in it's price range. The profile is sleek, elegant, and turns plenty of heads. 5 series and A6/S6 are a dime of dozen. I hope this helps you but remember these are all my honest opinions.