Had it 4 months now - it's great - the engine is brilliant, it never seems to do less than 40mpg on any long trip (Mid 40's if you're just on the Motorway), the mild hybrid system is cool, the interior is nice and its comfortable and refined. It also looks fantastic - the last year before they stopped making great looking cars. Imagine how good the M3 would look if it had the same front as the 2021 3 Series?
In 4 months I've averaged just 4mpg less than I did in my 530d, which is the big surprise. On a longer trip it's not quite as good as my 530d was in terms of refinement - there isn't really much if any more road noise thanks to the acoustic glass fitted to the front windows, but you can hear the engine at Motorway speeds which you never could in the 530d. But then it's a petrol 3 series not a diesel 5 Series, so really it's unfair to be too surprised or annoyed by this.
It really is just such a good 'everything' car. The performance is exceptional, it sounds great but it's also a completely normal 3 series when you want it to be. Great car - hopefully keep this for at least as long as I did my 530d (7 years!).
What don't I like about it?
The fuel tank is too small meaning even with it's efficiency you still have a maximum range of about 500 on longer trips and 250-300 around town.
The interior could be a little bit more luxurious - it can't have saved them much money having the door handle armrest made of soft plastic instead of leather, can it? That said it's still by far the best 3 series interior they've ever made.
Why is the exhaust just a bit of trim? A basic 320d has a twin exit exhaust at the back that has real pipes - why does the M340i have two bits of trim instead, which are not connected to what looks basically the same twin exit system fitted to the rest of the range
The ride quality wasn't great until I fitted a set of Michelin Pilot Sport 4S, now it drives properly
Why are manually operated seats anywhere near a car like this? Seriously? You need the Comfort Plus pack to get electric ones and that makes it even more difficult to find a car to buy as most of them have black wheels and black trim everywhere. I don't find it a practical issue as I never need to move the seat, but it makes an otherwise great looking interior look a bit cheap: