Over the lifetime of the car is there a significant difference in the break down rate for a BMW 328i 4 cylinder with turbo vs a 6 cylinder?
Yes. The majority of vehicles with turbo-charged engines will need a lot more maintenance than vehicles that are normally aspirated. It’s just a fact of life since most turbo owners don’t have a clue when it comes to turbo maintenance.
+1 @missileman
Yes!
No 4-cylinder offered. The choice is between the twin turbo 335 6-cylinder and the normally aspirated 6-cylinder in the 328. According to edmunds.com, the difference is in favor of the 328, but it is only $500 for maintenance and $700 for repairs over 5 years. An average of $240 per year is not enough to influence my decision.
More important is to buy the best maintained example you can find. If you find one that looks like it just rolled off the showroom floor, with all maintenance records, and a clean pre-purchase inspection, that one is worth buying.
“More important is to buy the best maintained example you can find. If you find one that looks like it just rolled off the showroom floor, with all maintenance records, and a clean pre-purchase inspection, that one is worth buying.”
+1
And, it is important that the maintenance invoices clearly state that the proper-specification European motor oil was used for each oil change.
When some car owners see the insanely high price charged for that oil, they make the very poor decision to “cheap-out” on the oil and that can have…expensive…consequences, especially with a turbo-charged engine and/or if they went for extended periods between oil changes.
The base engine in a 328 is the turbo four. I have it in my 2014 328, almost 30k and no problems. It’s fast and great on fuel.
As an “old-school” mechanic–how is that possible if I’m only 45?–I will take a big, slow-turning V-configuration engine over a high revving turbo 4 cylinder any day. They run cooler, slower, don’t require synthetic or special oils, and all other things being equal should last longer and be less trouble.
As a modern-day technician, I’d go for the 4 cyl turbo. Less weight, more power, better fuel economy, and it’s just fun to be a part of the latest technological advances.
Like it or not, the turbo 4 is becoming universal in cars from Chevy to Mercedes. Almost all makers now put them in just about anything. Two exceptions are Mazda and Honda for now. Toyota has started adopting them. As for BMW, most of their cars have the turbo 4 2.0 l in one or more models, like the 320i and 328i.
2011/2012 was the first model year for the 4-cylinder. The previous generation used the I-6 in the 328i.
Yes, there is a difference. But use good quality synthetic oil, change it regularly, and practice good “turbo karma” such as letting the car idle for a minute or two after hard runs before shutting it off, and you should greatly increase your turbo’s longevity.
Life is short. Buy what you want and what you will enjoy driving. Kicking yourself every day because you decided to play it safe and not get the turbo will not make you happy either. (assuming you want the turbo)
I believe the Turbo is the twin turbo. Either way the 6 on the 3 series has proven to be reliable, the 4 is new. You can look on the beemer forums but there are a lot of stories about the turbo self-distructing and causing engine damage in the process but I am not sure how those cars were driven. It is like the prolonged QT interval-waiting to happen 
Turbo 4’s have been around for a long, long time at BMW and other car makers. BMW’s first turbo 4 was offered in 1971. Saab introduced their turbo 4 in 1978 and have produced a version every year until their close in 2010.
As many here have pointed out, if you scrimp on maintenance, a turbo can bite you harder when it fails than a naturally aspirated 6. With the proper care they will last as long as any 6 cylinder. They will also save you gas and give you equal performance. That is why many manufacturers are adopting this technology. The last time this was widely available was the 1980’s when nearly every car maker offered a turbo 4. Some with success - Saab, Volvo, Mitsubishi, some without - Chrysler, Ford.
The Volkswagen and Citroen 2CV were for many decades icons of automobile reliability and their common significant asset was lack of complexity and unessentials. They were air cooled, had no power steering, no power brakes, and no aura of performance for the owner/driver to live up to. So few people value simple, above average reliability these days though.
I am currently driving 2015 WRX which has a turbocharged boxer 4 engine. During “normal” driving, the turbo very seldom goes in to a boost mode according to my onboard info screen. Unfortunately, when purchasing a pre-owned vehicle, unless the former owner is known on a personal level, there is no way to determine how the vehicle was driven, so service records may not be accurate. My neighbor drives a Lotus Exige and maintains it immaculately. However, he only drives it for autocrossing. I work for a manufacturer who has been offering turbocharged vehicles for over 37 years, and I can attest to the fact that I have personally seen less than 25 failures in that time. Buy what you like and enjoy it.