The BMW 125d is the most powerful diesel version of the BMW 1 Series hatchback yet.
Like the 116d, 118d and 120d, it uses a 2.0-litre engine, but this has been tuned to produce 215bhp 34bhp more than the 120d offers and 14bhp more than the previous-generation 123d.
The new 125d also averages 57.6mpg, while CO2 emissions of 129g/km put it in the 19% company car tax band; just one band above the 120d.
Efficiency improves to 58.9mpg and 126g/km if you specify the optional eight-speed auto gearbox, as fitted to our test car, although this isnt enough to bump the car into a lower tax band. The regular auto box costs 1490, while the Sport auto with paddle shifters costs 1600.
The 125d comes exclusively in M Sport trim, which brings a range of sporty touches, including 18-inch alloy wheels, sports seats and firmer, sports suspension.
Whats the 2012 BMW 125d like to drive?
The 2.0-litre diesel engine feels strong and flexible in all traffic conditions, while the smooth auto gearbox perfectly compliments it.
You can knock the box into a sport mode that makes it kick down earlier, but the engine produces so much torque (332lb ft) that there are few occasions where youd want or need to use this option.
Unlike most of its rivals, the 1 Series is rear-wheel drive, and this helps give it excellent balance. It darts into bends and then grips hard, while the steering is well weighted.
The firmed-up M Sport suspension also helps agility because it allows little roll in bends, but you feel every bump and imperfection on the road.
The 125d is no relaxing cruiser, then, although refinement is good, aside from a bit of road noise over rough surfaces.
Whats the BMW 125d like inside?
As with the rest of the 1 Series range, rear comfort is an issue. Head- and legroom are tight for six-footers, and the seats are a touch on the firm side.
The narrow door apertures mean getting in and out of the back is more awkward than it is in some five-door rivals, too.
The offset driving position that afflicts the 1 Series isnt as bad with the auto gearbox as it with the manual, but it may still be uncomfortable for some.
At least the dash layout is pretty faultless; the instruments are clear and the centre console is easy to navigate.
Most of the materials look smart, too, even if some plastics lower down arent quite as nice to touch.
The M Sport trim comes with all the gear youre likely to want, including sports seats, a DAB radio and BMWs slick iDrive system. It also brings a smattering of M Sport badges both in and out the car, plus a chunky leather steering wheel.
Should I buy one?
The 125d makes some sense as a company car because it combines its strong performance with low emissions.
The optional auto gearbox makes long journeys less arduous, too, but with the standard version fitted it bumps the price up to 29,310, which is 2380 more than the more comfortable and practical VW Golf GTD DSG.
If you are going to buy a 1 Series, the 120d is a better option. Its still fast and costs almost 2000 less than the equivalent 125d.
What Car? says