Early 135i's had the N54 twin turbo engine. Up to 2010 M.Y. Then for 2011 BMW switched to the single turbo N55 engine. The N55 has slightly less lag, and is slightly better on fuel consumption but less tuner happy.
All cars had problems with the HPFP(High Pressure Fuel Pumps) failing early. BMW NA & Canada extended the HPFP warranty up to 120K miles or ten years. So no big worries. Symptoms are long cold start cranks before the engine fires up to life.
All cars seem to need a new electric water pump and e-thermostat by 60K to 80K miles. ~$1K to 1.2K at the dealers... ~$700 at an indi or less, or ~$500 in parts DIY
OFH(oil filter housing gasket) seem to leak on all cars. Not a cheap repair(~$500 dealer) but DIY doable. $40 in parts
Carbon buildup on the intake valves can also be an issue... ~$500 to $700 at most dealers. Much less at Indi shops.
Brakes and Tires can be a bit pricey but thats about it. Our 1er's are fairly reliable and very much so fun to drive!
Difference between "sport package" and "M sport package"?
https://www.1addicts.com/forums/showthread.php?t=362052
The Ultimate 1-Series Buyer's Guide
https://www.1addicts.com/forums/show....php?t=1285231
Cars for Sale
https://www.1addicts.com/forums/forumdisplay.php?f=268