Reliability of C8 3.0T Powertrain

[jftormen]

Hey Guys,

I dont normally make posts on forums (so please forgive my poor post etiquette) but I did not see one on here about this topic. I like Audis and am in the market for a car. I had a 2012 Audi A6 3.0T which I liked but I no longer have that vehicle. Im very familiar with that platform and its reliability and worked on the car myself (changed pcv, diagnosed various issues, etc.) Im thinking about another A6 and thought Id go C7.5 but I thought I may as well ask about the C8 platform since its so close in price for a Premium Plus nowadays.

Is this car reliable? How easy is it to work on yourself? Any fatal flaws? I get that its an Audi and Im not asking if its a Camry. Im just not looking for a money pit and plan to tune the car so Id like something that could hopefully treat me about as well as my C7 did, and like I said Im fine doing the work myself...though Ive never worked on car with a turbo, cant be too different right

Anyways, Id really appreciate any input!

Some side notes:
Im willing to spend around $20k (Ive seen C7.5s as low as $15k with around 80k miles but its hard to find nice Prestiges, especially ones with ACC)
Not set in stone on an A6, I like cool looking cars that are quick - Want Audi because they are imo the best looking cars and the supercharger gets me moving. Dont care too much about top end, just 0-60
Am considering a Tesla, totally different topic I know but thought Id throw that out there too

[JustNick]

Hey Guys,

I dont normally make posts on forums (so please forgive my poor post etiquette) but I did not see one on here about this topic. I like Audis and am in the market for a car. I had a 2012 Audi A6 3.0T which I liked but I no longer have that vehicle. Im very familiar with that platform and its reliability and worked on the car myself (changed pcv, diagnosed various issues, etc.) Im thinking about another A6 and thought Id go C7.5 but I thought I may as well ask about the C8 platform since its so close in price for a Premium Plus nowadays.

Is this car reliable? How easy is it to work on yourself? Any fatal flaws? I get that its an Audi and Im not asking if its a Camry. Im just not looking for a money pit and plan to tune the car so Id like something that could hopefully treat me about as well as my C7 did, and like I said Im fine doing the work myself...though Ive never worked on car with a turbo, cant be too different right

Anyways, Id really appreciate any input!

Some side notes:
Im willing to spend around $20k (Ive seen C7.5s as low as $15k with around 80k miles but its hard to find nice Prestiges, especially ones with ACC)
Not set in stone on an A6, I like cool looking cars that are quick - Want Audi because they are imo the best looking cars and the supercharger gets me moving. Dont care too much about top end, just 0-60
Am considering a Tesla, totally different topic I know but thought Id throw that out there too

If you're planning on doing any modifications past a tune, I would caution against an A6. The aftermarket has left me... wanting. There's some question marks around early C8 transmissions and some users are finding that they are failing with spirited driving (some with normal highway driving too). I myself haven't had this problem with an APR stage 1 93 octane tune and have been very happy with the car overall.

If I were to do it again, I'd go S5. The support is there, and there's more units out there for a larger sample size for any issues that may crop up. $20k for a Prestige is going to be a tough find, I paid $40k for mine with 45k miles earlier this year. I'm still very happy with the car overall, its super comfortable and very sharp looking, but I'm a modder at heart so I feel a little burned by the lack of go fast goodies that everyone else is getting for the same engine platform. Since we have a different transmission than the rest of the EA839 vehicle family and we have relatively low units sold, we're often an afterthought.

[jftormen]

Thanks for the input, Im assuming the major issues are related to the transmission then and not the engine. Would still be curious about the serviceability of the car myself. Id probably never really go past stage 2 on anything so the lack of a comprehensive aftermarket does not have as much of an affect on me. The S5 (and A5) looks absolutely stunning imo, and if I had to go with the 3.0T (Turbo) Id probably opt for that one on looks alone. I just would prefer a car with 4 doors as I often bring people with me. I also am trying to veer from S models as I would think it would be significantly more on insurance. Maybe there is a case to be made for the sportback? The $20k I was referring to was for the C7.5s. I could go higher but thats when I start thinking, should I spend $25k on the perfect C7.5 or spend that on a decent C8.

Either way, I will definitely consider the S5 though Id probably venture to say Id be lucky to get one under $30k, but itd definitely have less miles than anything Im looking at rn. Thanks again for your input!

[LegoManiac]

The 48v hybrid system would be my concern.

Not many people running tunes C8 3.0ts, and seems about 50/50 that the ones that are had transmission issues.

For your budget, and what you’re looking to do for mods, I’d pass on a C8. A S4 or S5 SB with the ZF 8 speed would have more headroom.

[jftormen]

The 48v hybrid system would be my concern.

Not many people running tunes C8 3.0ts, and seems about 50/50 that the ones that are had transmission issues.

For your budget, and what you’re looking to do for mods, I’d pass on a C8. A S4 or S5 SB with the ZF 8 speed would have more headroom.

Are you referring to those with the supercharger or turbo? I didnt know any S4s or S5s came with a ZF 8 and Id definitely consider an S4 with a ZF 8

[LegoManiac]

Are you referring to those with the supercharger or turbo? I didnt know any S4s or S5s came with a ZF 8 and Id definitely consider an S4 with a ZF 8

The B9 S4 and S5 (as well as the SQ versions) have the ZF 8 speed.

[randomdude85]

The 48v hybrid system would be my concern.

Not many people running tunes C8 3.0ts, and seems about 50/50 that the ones that are had transmission issues.

For your budget, and what you’re looking to do for mods, I’d pass on a C8. A S4 or S5 SB with the ZF 8 speed would have more headroom.

I agree, I love my C8 but I wish there was a transmission tune so I could confidently add power, that would make the car perfect.

[DutchK23]

Are you referring to those with the supercharger or turbo? I didnt know any S4s or S5s came with a ZF 8 and Id definitely consider an S4 with a ZF 8

I am running the APR Stage 1 (93) on my 2019 A6 C8 55 Prem. + and have had no trans issues...it is my daily driver so I am by no means launching it at every stop light but passing on the highway with the tune is quite nice (also note the torque limited version came out around the time I did the tune and so I don't know for certain I have that version).

I second/third LegoManiac's comment about the starter generator (lots of threads/posts about that) so I'd make sure that had been replaced before buying. No issues otherwise although I have been doing oil changes at 5K since the tune and did wait until after the warranty expired...

I also installed a module to disable the horrible AS/S and am contemplating also adding the APR CAI as well but am a little concerned about the increased noise.

hope you enjoy it if you decide to purchase and welcome to the community I have found it quite helpful

[xenonzuk]

I am based in the UK and running a custom map with the following modifications:

Milltek Downpipe
Wagner Intercooler
Custom intake
TS Hybrid Turbo
ECU tune
DSG tune

582 bhp and I have daily driven the car for 1 year with no issues.

[xenonzuk]

And a full custom exhaust system

[maxvq35]

Stage 1 APR since 40K on my '19 A6 55Tfsi. Bought it as a CPO w/ 34k miles May 2022. (


Just hit 65K Feb 2024 (so my daily driver business use is ~17k mi a year) and at my oil service dealer discovered coolant leaks around coolant shutoff valve. So that led to new Water Pump, Thermostat , coolant shutoff valve, waterpump vaccum solenoid and the accompanying parts and labor... $2600.

I've never replaced a waterpump before on any of my cars. I had a 02 Maxima hit 140k/8 yrs, '17 Volvo S90 hit 100k/5yrs , and a '08 528i hit 190k/10 yrs on their original parts.

So i don't know if this is just a common Audi thing or attributable to the tune or what not. But other than that and the starter generator issue (factory part issue).... @ 65k miles with a tune just a bad waterpump/system leak. Trans holding up ok, only had a fault message once on the highway while i was getting on a lengthy spirited high speed hard pulling and went away after the next restart.

[randomdude85]

I am based in the UK and running a custom map with the following modifications:

Milltek Downpipe
Wagner Intercooler
Custom intake
TS Hybrid Turbo
ECU tune
DSG tune

582 bhp and I have daily driven the car for 1 year with no issues.

where did you get a DSG tune? I haven't been able to find anyone with a tune for the C8 A6 trans

[JustNick]

where did you get a DSG tune? I haven't been able to find anyone with a tune for the C8 A6 trans

Yeah, what he said! And where did you find a tune for that turbo combo on this platform? Please share your secrets so that I may sink more money into my car