The Touring is the estate version of the 3-Series saloon which went on sale earlier this year, and as is generally the way of these things the two cars are identical from the centreline forwards. Unlike the very first 3-Series Touring launched in the 1980s, which was undeniably pretty but not much of an estate car, this one becomes more practical as you go further back.To the nearest millimetre, it's exactly the same length as the saloon, but it offers 15 more litres of luggage volume with the rear seats in place, and, thanks to a slightly higher roofline, 35 more than the previous Touring did.That brings the total to 495 litres, which is slightly more than its most obvious rivals, the Audi A4 Avant and Mercedes-Benz C-Class Estate, can manage. With the rear seats folded, the capacity increases to 1500 litres, matching the shorter C-Class and easily beating the longer A4.If you're going to use the Touring as a serious load-carrier you'll need to open the tailgate. That may seem clunkingly obvious, but it's worth mentioning because BMW also offers the possibility of accessing the luggage compartment by opening the rear window. The aperture thus revealed is fairly small, but it's useful if you're putting light items rather than suitcases into the car, and it can be used in tight spots where opening the tailgate would be impossible, or at the very least inadvisable.As well as the extra luggage space, BMW has also created more room for rear passengers in the new Touring, but there still isn't very much of it. Sitting in the back, I found it difficult to get my feet under the driver's seat, and the top of my head made light contact with the roof. Okay, I'm six foot three, but I would have hoped for better than this in what is hardly a small car. Up front, an extra inch of seat travel would have made driving that little bit more comfortable too.To make up for that, the driving experience is greatly enhanced by the 330d's three-litre six-cylinder turbo diesel engine. The least good thing about this engine is that it sounds a bit rattly under hard acceleration, but it certainly provides sturdy straightline performance. With the help of an eight-speed automatic transmission which is the star turn of every BMW it's fitted to (and is the only gearbox available in the 330d), it allows you to accelerate from a standstill to 62mph in under six seconds if the mood takes you, yet it also uses fuel at the belief-beggaring rate of 55.4mpg on the EU test cycle.This was too short a test for me to investigate how realistic the official economy figure is, but no matter how you drive the car you're taxed as if it's emitting 135g/km (whether or not it actually is), so annual Vehicle Excise Duty payments are a relatively modest £120. Or, if you like to look at it this way, less than 50p per year for every bhp the turbo diesel produces at full chat.It's a heavy engine, of course, and that might contribute to a slight unwieldiness in the handling which the test car's £750 optional M Sport adaptive suspension couldn't sort out. For that reason, if I were in the market for a diesel 3-Series Touring, I'd probably go for the 320d instead, since it's cheaper, adequately quick and even more economical, and (if the saloon is anything to go by) is no doubt just that little bit more agile.The 330d is available only in the SE and Luxury trim levels. The latter costs £2500 more, and most of what you get for that is extra styling equipment, though the higher spec also includes a multifunction sports steering wheel and Saddle Brown leather upholstery which, despite being dark, cheers up what would, in all-black, be a none too inspiring interior.In its basic form, without the adaptive suspension mentioned previously, the 330d Luxury will set you back £37,200, but it seems unlikely that anyone prepared to buy a car like this will be content without satellite navigation, Bluetooth phone preparation or a USB audio interface. They are all part of the BMW Professional Multimedia package, which also includes BMW Assist and costs an extra £1995.Other options that I imagine will be taken up by most buyers include adaptive xenon headlights (part of the £925 Visibility pack), electric front seat adjustment (£910), front seat heating (£300) and lumbar support (£235), DAB digital radio (£305), a head-up display (£800), the surround-view camera system (£500) and perhaps the panoramic glass sunroof (£1155). I'll leave you to make your own judgement about what kind of profit margin BMW must have built into those prices. Engine 2993cc, 6 cylinders Power 258bhp Transmission 8-speed automatic Fuel/CO2 55.4mpg / 1355g/km Acceleration 0-62mph: 5.6 seconds Top speed 155mph Price £37,200 Details correct at publication date