Engine and gearbox
Despite there being six 3-series models on sale prior to the M340i’s appearance there are effectively just three engines, one 2-litre four-cylinder petrol turbo, one 2-litre four-cylinder diesel and one 3-litre inline six-cylinder for the 330d.
Until the M340i xDrive arrives the most powerful model is the 330d which develops 261bhp and a hefty 428lb ft of torque. Combined with the familiar eight-speed ZF automatic with steering wheel-mounted paddles it’s a pretty effective combination and if it’s combined with xDrive traction is quite exceptional, allowing the 330d to transfer all of that torque to the road very effectively. Its mid-range is mighty and the bassy, gravelly soundtrack is pretty good for a diesel.
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The 318d (148bhp, 236lb ft) and 320d (187bhp, 295lb ft) both use the B47 modular diesel engine and while the 318d’s stats might not look particularly meaty it still goes pretty well. The 320d is by far the better of the two though, making good use of its additional power and torque. If you must have a manual 3-series then you’ll need to choose one of these two models as they’re the only ones available with three pedals, and even then, BMW expects uptake to be pretty low. The manual gearbox, it would seem, is on its last legs.
The petrol models (bar the M340i) all use the same 2-litre unit but in different states of tune. The 320i offers 181bhp and 221lb ft of torque while its 330i sibling doles out 254bhp and 295lb ft of torque. The 330e adds an electric motor for a combined maximum output of 288bhp and an all-electric range of up to 41 miles. Given recent company car tax breaks there’s no doubt this will be a big seller.
While there’s nothing desperately wrong with the four-cylinder turbo unit it’s not particularly inspiring either. Power and torque delivery is fine and there’s very little lag to speak of, but aurally it’s pretty disappointing and when this is added to the 3-series’ overall improvement in terms of refinement the overall picture is slightly less sporting in feel than it was before. The 330d is over £2k more expensive than the 330i, but it gets out vote over the 330i if you’re looking for a performance-orientated package.
The M340i xDrive is the only petrol-engined 3-series with a six-cylinder inline engine and it should be pretty special if our brief encounter with a pre-production example is anything to go by. Yes, it’s only offered with all-wheel drive, and yes, it’s auto only, but with 369bhp and 369lb ft of torque it’s rapid, and perhaps most importantly (when compared to the rest of the range) it’s tuneful, too.