The BMW 320d xDrive gets the same 184bhp four-cylinder diesel engine as the standard 320d saloon, but adds the security of four-wheel drive.
Asking the engine to drive two extra wheels hurts efficiency, but only slightly; average economy falls from 61.4mpg to 57.6mpg, while CO2 emissions rise by 8g/km to 128g/km.
We drove the saloon, but BMW has also applied the xDrive treatment to its 320d Touring, and it expects xDrive models to account for around 4% of all 3 Series cars sold in the UK.
There aren't many direct rivals, but the xDrive will face competition from the 2.0 TDI quattro versions of Audi's A4 and A5 Sportback, as well as Skoda's 2.0 TDI 4WD Superb.
What's the 2013 BMW 320d xDrive like to drive?
The xDrive system can send up to 100% of the 320d's 280lb ft of torque to either axle to help combat any loss of traction on slippery surfaces. Most of the time, though, there's a 60/40 split in favour of the rear wheels.
It's a relatively lightweight system at 70kg and, importantly, it works effectively, meaning the xDrive is every bit as rewarding as the rear-wheel-drive 320d. In fact, its superior traction gives you greater confidence when placing the front of the car into bends.
Switch to the Sport mode on our test car's optional M Sport suspension and that confidence grows, because the steering getting weightier and the suspension stiffer.
True, the ride is slightly more supple if you leave the car in Comfort mode, but even in Sport it never becomes harsh.
Flicking through the modes also alters the speed at which the optional automatic 'box swaps gears. No matter which you mode you select, though, the 'box is rarely caught out.
The 320d's engine is a punchy performer. However, it sounds grumbly around town, and while it fades into the background at higher speeds, you hear a considerable amount of wind noise from around the door mirrors.
What's the 2013 BMW 320d xDrive like inside?
Inside, the xDrive is no different to any other 3 Series saloon, and that's no bad thing.
Almost everything you can see and touch is suitably classy, and there's plenty of room in both the front and rear for tall adults.
The boot is a good size and shape, too, although you need to pay an extra 390 if you want split-folding rear seats.
The cheapest 320d xDrive comes in SE trim, and this gets you dual-zone climate control, rear parking sensors, Bluetooth, automatic lights and wipers, a USB connection and alloys.
Should I buy one?
For those who've been caught out by the UK's recent cold winters, or who live in an area where owning an all-wheel-drive vehicle is a must, this xDrive 3 Series is worth the £1500 premium.
It retains the 3 Series' superb handling dynamics without increasing running costs by too much.
Company buyers shouldn't be put off, either, because the 320d xDrive sits just one company car tax band higher than the standard saloon its higher CO2 puts it in the 20% band.
However, for the majority of private and company buyers who don't really need four-wheel drive, we'd recommend saving some money and sticking with the rear-wheel-drive 320d.
What Car? says...
BMW 320d xDrive
Engine size 2.0-litre Price from £29,910
Torque 280lb ft
0-62mph 7.5 seconds
Top speed 145mph
Fuel economy 57.6mpg
CO2 emissions 128g/km