2013 BMW 650i xDrive GC vs 2013 Audi S7

[itzjoker]

Been shopping around for a 650XI but recently came across some Audi S7 and they are similarly priced. Was wondering if anybody has some input on reliability/cost of maintenance for both cars with higher mileage (80k+)

Definitely need the AWD for winters.
S7 has more power and higher potential in regards to upgrading which is extremely attractive to me.
S7 seems to have more rear passenger space and trunk space.

I'm hesitant with buying either cars with high mileage because of the turbos/reliability. I've done some research on the S7 and turbos are known to go out, but can be saved/prolonged with some servicing to the screens (~$2,000) before failure. I'm fairly confident I can change them out myself if it comes down to it. Not sure on reliability of the BMW N63TU motor.

I was set on a 650XI but now I'm leaning towards an S7.

What are some other things I should look out for on a higher mileage S7? My last car was a B6 S4, bought at 100k miles with the timing chain serviced and owned it for 5 years with little problems so my experience with Audi has treated me well. I've test driven an S6 and it was a blast to drive. The interior of my '16 X6 feels much more solid and higher quality, but that could be that it's much newer. I'm torn.

My biggest factor for choosing one over the other would be cost of ownership/reliability. I only plan on having either car for 2 years max and would not like to burn a hole in my pocket.

[TechCom-Mike]

Six of one, half a dozen of the other I'm afraid. As you note the S7 turbo issues are well documented but, before I bought my A6 3.0t I was quite keen on a BMW 550i (having had two 335i's in succession) until the service guys I'd got to know at my local BMW dealer actually talked me away from it, trying to steer me to a 535. Pretty much the N63TU has the same problems as the S7 due to the turbo sitting in the hot Vee, makes it much more prone to failure, not to mention BMW quietly advising customers to replace their battery at every single annual service due to all the fan cooling that goes on after switching off the car. So in either 650 or S7, reliability seems a dubious detail of both and you need to really know the cars' history (I'll admit 80K+ sounds scary to me), be absolutely rigorous with your own maintenance and philosophical to the prospect that one day it may all go bang anyway.

[PynkFloydd]

I can speak to the N63 engine since I've torn mine down and did a pretty thorough analysis with the N63TU. One very important thing to note is that there were reports of bad piston rings on some early 2013 N63TU engines where there was excessive oil consumption that's only solved with an engine replacement. For that reason alone, I'd skip the 2013s entirely and go right to 2014 (especially since there were a lot of new features added to 2014 6-series).

Also, FYI, my battery is ~4 years old and fine. It could use a replacement, but it still starts up instantly after a week or two of sitting in the garage untouched.

The good thing about the N63 is that it does NOT suffer from the same issue as the S7. Similar concepts, but very different. BMW actually learned a lot from the original N63 and fixed the problem areas with the N63TU, which were further improved upon after 2016.

Some parts prone to failure on the original N63 that were eliminated with the TU revision are:
-Electric blow-off valves that'd fail from the gasket around the solenoid cracking were replaced by a new VANOS system that adjusts timing on the fly.
-Plastic CCV lines were replaced with ones that eliminated the plastic that'd get brittle from heat.
-Leaky injectors with nozzle opening outwards was replaced with new injectors that have a nozzle that opens inward to prevent leaks.
-Valve seals prone to failure were replaced with updated versions.
-Turbo CHRAs were completely redesigned.

The oil lines plugging up in the N63 aren't that common... The biggest issue is/was the valve seals failing from the high heat. I replaced mine and at their worst, I was consuming about a liter of oil every 300 miles. After replacement, I may add a liter 1x between my usual 10k oil change and I'm at 130k miles and still haven't replaced turbos. Another pain point on the N63 I've had to replace is the oil line to the front coolers, which tends to fail after hitting 110k+ miles.

One thing that's a pain with the N63 is that it requires dropping the subframe to perform any major maintenance, so that can make repairs costly/time consuming. There's no good way to access the intake without dropping the engine, so a cleaning is a $7k job at the dealership.

If that doesn't bother you, the rest of the car is bulletproof. The suspension is fairly maintenance free and might require wheel bearings around 100-120k miles and you'll just have usual maintenance items. ...this is in direct contrast with my A7 (with same suspension as the S/RS7) that required a suspension rebuild and new bearings by 80k miles.

Also, if you plan on doing maintenance yourself...BMW's Rheingold is far superior to Audi's ODIS and the Chinese clones to interface with the car are also better for BMW.

My #1 complaint with the N63 engine is gas mileage. I usually get around 13mpg city and 21-23mpg highway with maybe 18mpg mixed and it's tough to swallow the ~$80 fill-up. I've been tempted to replace my A7 TDI and 750i with a recent 740i, but I like the current BMW redesign so much that I'm waiting a few more years to get a used 850i or 2019 740i.

[itzjoker]

Thanks for the input fellas.

Dropping the subframe on 650 to perform major maintenance is a huge put off for me. I feel the S7 will be easier to maintain due to all the support on this forum and that is a huge plus for me. The 650 forums don’t seem too involved when it comes down to DIYs/tech etc.

The S7 I’m looking at seems to have been taken care of well. I see that it’s been serviced for every 10k miles up to the 75k maintenance. I might bite.

[kpriv]

With 10k service intervals, I’d check the turbos for shaft play before buying. If they are ok, pull the trigger and either diy the oil screen or pay to have it fixed immediately. Not worth the risk, and if you do it you should be able to get your 2-3 years out of it without perpetual worry.

Sounds like you are handy enough to tackle the job. I’d rate myself a 5-6 on the mechanic scale and with a buddy helping I was able to do it in connection with going stave 3.

Good luck!


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[PynkFloydd]

Dropping the subframe on 650 to perform major maintenance is a huge put off for me. I feel the S7 will be easier to maintain due to all the support on this forum and that is a huge plus for me.

It really depends on your abilities, garage space and toolbox. Dropping the subframe on a BMW is intimidating, but easy. Dropping the whole engine is not. If you get an extended warranty, you shouldn't have to worry about major maintenance before 100k miles and there was a recent recall that should have replaced injectors (which I believe were covered also for the N63TU in the CCP campaign).

Audi is better about making repair instructions available to consumers on their erWin site, but BMW is far superior with software updates and diagnostics. With Audi, you need to dig through TSBs for update codes and have a live monthly subscription to perform any updates. BMW uses a database and rolls out regular comprehensive updates. You're lucky see a single update for a module for the life of the car with Audi (and far more likely to experience software bugs that never get fixed). ...also, Audi requires costly recalibration for the drivers assistance if you do any suspension work, windshield or part replacements. BMW usually does not.

Both cars have their strengths and weaknesses. I was in the same position and ended up trying Audi. I do think the Torsen Quattro on the C7 and C7.5 is the best AWD system out there, but the steering is a bit lifeless. For high mileage repairs, you're probably looking at similar costs. The S7 may be slightly easier to repair mechanically, but definitely not with electronics.

I'd suggest going with what car feels better and getting a warranty.

[Audibellybutton]

I am a huge BMW/BENZ/AUDI fan, I’ll admit I’ve owned all but don’t know as much about Audi’s, however, I will day from a bmw fans perspective, stay away from the N63. It’s bad, poor design, unreliable. Almost as bad as those WRX engines... Almost. I’ve heard the S7 has its issues too, other people can elaborate on that but I would still choose the Audi. Generally anything that ends with “50i” from the past decade would be a huge no from me, other than the 850 from this year... MAYBE

[BillyBawb]

Both cars will be a bit dear to maintain, but I'd pick the S7 any day of the week, and twice on Sundays.

N63TU's are luck of the draw... and can still go pretty badly wrong if you get a lemon.

S7 turbo core replacements are cheap these days, and considering that you're intending to modify it anyways, the S7 is a no-brainer here.

Do it, do it.

[19birel]

Avoid the N63, in addition to turbo failure the valve seals tend to fail early on causing high oil consumption (according to BMW 1qt per 700miles is ok) and total engine failure is not uncommon as a result of oil starvation. There have been revisions of the motor with better heat shielding and so forth but a 2013 model year won't have that. From my understanding your safest bet is the Audi.

For what it's worth the latest crop of those engines (the TU3 variants) have a host of updates that should make them more stout, but that's not strictly relevant here I suppose