Originally Posted By: Kiwi_ME
It's about time. BMW's current NA 4-cyl engines are pretty good.
Originally Posted By: SteveSRT8
NVH issues prevent many of us from enjoying almost any inline 4.
For the last decade BMW's fours use balance shafts if the displacement is high enough to be required. My mother drives a 320D (2 L 4-cyl turbodiesel) and it's smooth and pulls strong.
Yes, the only I4 I've really liked was the 3.0L longitudinal I4 with Variocam and harmonic balance shafts in my Porsche 968. Smooth, torquey and quick. It had a lot of parasitic loss at light throttle angles between the 11:1 compression and the cam profile and drove a bit like a big block I guess. All others I've experienced seem to have a lot of NVH. As a driver of predominantly manual transmissions, I like having more cylinders firing when you're working the clutch down near idle - smoother launches and far less chance of a stall with low rpm take offs.
This is not to say that I wouldn't rule out the new BMW I4s without sampling - I have an open mind.