Initially, the TT came with a 178bhp 1.8 TFSI petrol engine, a 227bhp 2.0 TFSI petrol (306bhp in the TTS), a 395bhp 2.5-litre five-cylinder petrol exclusive to the TT RS, or a 181bhp 2.0 TDI Sep 30, 2015. #1. Seems that BMW & reliable don't do together. At least that's what I can gather from owners. The way I see it however is they are more needy then a Honda and require prompt service on the expected mileage intervals. I'm fine with that since I've been doing just that with my vw tdi and haven't had any problems yet. *knock on wood*. Save up to $11,170 on one of 160 used 2015 BMW 3 Series Diesels near you. Find your perfect car with Edmunds expert reviews, car comparisons, and pricing tools. z8kUO.