Honestly? I'm in two minds about the B-Class. In some ways it irritates me, yet I loved driving it and wished I'd been able to spend more time with it before sitting down to write this review.It's an MPV, and there would be no point in buying one of those if you weren't able to carry a lot of stuff in it. The B-Class scores well here, with a rear-seats-up luggage capacity of 666 litres - a slightly ominous figure when you consider how many liars and charlatans have been pretending that the world will end the day after this article is published. With the seats folded the volume increases to 1545 litres, which isn't a number that should bother you unless your name is Mary Rose.There's no question, then, that Mercedes offers its B-Class buyers a lot of practicality. The company perhaps missed a trick by requiring you to use both hands to fold down the rear seats, but full marks to the designers for providing such a low boot floor.Back in the days before MPVs were called MPVs they were known as "people carriers", and that leads me to a criticism I wasn't expecting to have to make of a nearly 4.4-metre long car. I'm above-averagely tall, but not so tall that I should have trouble sitting in the back of a B-Class behind a driver's seat set to my requirements.I did, though. Depending on where I put them, my knees were jammed into either a folded-up tray or the surroundings of a cargo net, both made of unyielding plastic (meaning, in the latter case, the surroundings rather than the net, of course). In models without those items there wouldn't be a problem, but it was still rather a surprise.The styling of the B-Class is handsome enough, though I don't think much of the upswept crease on each side - too fussy - and more attention could have been paid to helping those inside see out. The front and central pillars are obtrusive, and the rear side windows are just pathetically small.But my, what a splendid car this is to drive. The B 220 CDI's 2.1-litre diesel engine produces a maximum of 168bhp, which seems absolutely ideal. It gives you all the performance you need without ever putting the chassis under too much stress. The engine is also very quiet no matter how hard you're driving the car, and efficient enough to record 67.3mpg on the EU test cycle, though I didn't have the car long enough to establish how close to reality that figure is.Officially, the 220 CDI emits CO2 at the rate of 120g/km, which is actually 1g/km less than the official figure for the more economical and much slower B 200 CDI. This anomaly becomes all the stranger when you realise that the 220 costs just £30 per year to tax, or £70 less than the 200.For an extra £1460 over the cost of a 220 CDI manual you can have the seven-speed semi-automatic transmission fitted to the test car which actually improves acceleration and combined fuel economy (mostly because it works better in urban situations) though not the CO2 output. The selector for this sticks out of the steering column like an indicator stalk, which takes a bit of getting used to but has a lot to commend it, and the gearchanges themselves are fantastic - almost unnoticeable if you're going slowly, crisp and smooth if you're kicking ass.The steering is even better. It's firm but not heavy, and so refined in operation that I would almost believe any Mercedes employee who tried to tell me that a large vat of the highest quality cream was included somewhere in the mechanism.The suspension - 15mm lower than standard in the otherwise completely unsporty Sport - isn't suited for large bumps in the road, but does give the B-Class fabulously high ride quality for a car fitted with 18" wheels and low-profile 40-section tyres.The test car was very well-equipped, but that's because Mercedes had loaded it with so many optional extras that its list price jumped from £27,880 to £38,275. Foremost among them is COMAND Online, an undoubtedly comprehensive package which includes a radio, a 7" colour display screen, satellite navigation with traffic alerts, voice control, internet access (assuming you have an appropriate mobile phone), 10GB of music storage, an SD memory card slot and the ability to plug in almost any media device. It costs £2100 but doesn't include DAB digital radio, which will set you back a further £430.Other important extras are the panoramic sunroof at £1195 and the Exclusive package (Lava Black leather upholstery, high-gloss Black Ash wood trim, black headlining, velour floor mats and heated front seats) at £1055. Engine 2143cc, 4 cylinders Power 168bhp Transmission 7-speed automatic Fuel/CO2 61.4mpg / 120g/km Acceleration 0-62mph: 8.3 seconds Top speed 137mph Price £27,880 Details correct at publication date