Does the A3 1.8T require premium fuel?

[grnfool]

Does the A3 1.8t require premium unleaded fuel? My GF has been using Premium fuel on her 2015 A3 1.8T as recommended by Audi. However, when I was researching the 2014 VW Jetta 1.8T for my sister I noticed that VW recommends regular unleaded fuel. In comparing the engine specifications, they appear to be the same to me: HP, torque, bore, etc. I don't think she would mind saving some $$$ at the pump if there's no difference.

I did a quick search in the 1.8t forum but gave up after the third page.

[mpsmith]

Yes. 91 min.

[JoshDub]

You wouldn't really save any money anyway as you get better mileage with premium.

[Penti]

JoshDub - How would you get better mileage? Isn't the higher RON value just better knock resistance under compression!?

grnfool - Are the compression ratios the same for the two engines? Personally I'd just stick with the manufacturers recommendations. Better safe than sorry.

[SFV A4]

It will run on lesser fuel, but at reduced performance and possibly lower mpg's. Not worth it in my opinion. Could also run the risk of carbon build-up/clogging/fouling as the miles pile on years from now.

[grnfool]

grnfool - Are the compression ratios the same for the two engines? Personally I'd just stick with the manufacturers recommendations. Better safe than sorry.

From what I have seen on the web, the compression ratios are the same. 9.6:1 for both A3 and Jetta 1.8T

[grnfool]

It will run on lesser fuel, but at reduced performance and possibly lower mpg's. Not worth it in my opinion. Could also run the risk of carbon build-up/clogging/fouling as the miles pile on years from now.

Will it? I agree that it'll run on lower octane fuel, but will it be at reduced performance and fuel economy? If the two engines are the same and same tuning is similar that there should be minimal difference., especially when the engine hardly sees revs above 3500 rpms. Also, lower octane fuel doesn't mean dirty fuel, it just means it's more prone to pre-ignition.

[AUDITOPGUN]

Yes 91 my ex ran 89 on our old A3 and at 90k miles the car died on us open the engine and it was not pretty black gunk all over pistons $700 to fix

[Westlake]

Easiest way to find out what's required is to read the manual. My 2005 A4's manual says 91 octane is recommended, but not required. I've been using 87 for years. 125K miles and no fuel problems.

[LINDW4LL]

I'd just run it, although I'm not sure if it's required or not; I'd certainly assume so. Turbo engines usually require premium fuel, and run better on them as well.

Premium is about ~ $2.60-$3.00 more per tank on average than regular. That's approximately $150 a year if you drive 370 miles a week, which is likely more than average. Hardly worth worrying about.

[grnfool]

It will run on lesser fuel, but at reduced performance and possibly lower mpg's. Not worth it in my opinion. Could also run the risk of carbon build-up/clogging/fouling as the miles pile on years from now.

How do you explain the Jetta's equal power and fuel economy on regular unleaded? Also, carbon build up isn't an octane issue from my understanding of the issue.

Yes 91 my ex ran 89 on our old A3 and at 90k miles the car died on us open the engine and it was not pretty black gunk all over pistons $700 to fix

Sounds more than just a fuel issue based on Westlake's post.

Easiest way to find out what's required is to read the manual. My 2005 A4's manual says 91 octane is recommended, but not required. I've been using 87 for years. 125K miles and no fuel problems.

Yes, I read the manual. I'm now curious if the recommended premium fuel is just a marketing scheme.

I'd just run it, although I'm not sure if it's required or not; I'd certainly assume so. Turbo engines usually require premium fuel, and run better on them as well.

Premium is about ~ $2.60-$3.00 more per tank on average than regular. That's approximately $150 a year if you drive 370 miles a week, which is likely more than average. Hardly worth worrying about.

I had thought the same about turbo engines until I filled the tank on the Jetta. $150/yr isn't much but it's a nice night out on the town.

[gamegenie]

[grnfool]

Gamegenie - I've heard everything in the video before. My question has evolved to, what are the differences between the 2014 VW Jetta 1.8T and the 2015 Audi A3 1.8T?