Category: Small Family 
Price Range: £18,424 to £22,070
Roomy, reasonably practical and usefully family-sized; excellent crash protection; fuel-saving stop-start tech in some models; optional auto-parking system
Expensive; not especially refined; uninspiring to drive; awkward styling; cheap-feeling cabin
The Mercedes badge is about all the B-Class has to distinguish itself from its opposition; there are numerous more accomplished all-rounders now on the market.
The front seats are high and upright, giving a good view ahead, and all-round vision is unobstructed. The B-Class is an easy car to manoeuvre, with well-weighted speed-sensitive power steering to keep it light at low speeds, and if parking's a problem, the car can do it for you: the optional Active Park Assist system sizes up the space using ultrasonic sensors, sorts out the steering into it, and all the driver needs to do is work the accelerator and brakes. Also new is hill start assist in manual models, to prevent you rolling backwards.
At higher speeds, it's less impressive; though the adaptive suspension contains body roll well (and there's standard stability control) you never quite lose the sense that this is a high-roofed, top-heavy hatch, and the B does feel rather lumpen and ponderous.
The diesels are the stronger performers though neither is particularly quick: the B180 CDI (109bhp/184lb ft) does 114mph and 0-62mph in 11.3 seconds with the six-speed manual gearbox, and 111mph/0-62mph in 11.8 seconds with the Autotronic CVT, an easy-to-use, smooth and sophisticated clutchless set-up with sequential-shift function. The B200 CDI (with the same 2.0-litre engine tuned for 140bhp/221lb ft) can do 124mph/0-62mph in 9.6 seconds (manual) or 121mph/0-62 in 9.7 seconds (Autotronic).
The petrols are workaday but adequate: figures for the A150 (95bhp/103lb ft) are 108mph/0-62 in 13.2 seconds (five-speed manual) and 104mph/0-62 in 14.2 seconds (Autotronic) and while the A170 (116bhp/114lb ft) can do 114mph/0-62 in 11.3 seconds (manual) or 112mph/0-62 in 12 seconds (Autotronic) it will lack the mid-range pull and overtaking ability of the B200 CDI. The petrols are quieter, though, and vibrate less when idling.
We've not tested the stop-start system (badged Blue Efficiency) in the B-Class as yet, but in the A-Class, it cuts the engine and restarts it again almost imperceptibly, once you get the hang of lifting the footbrake and dipping the clutch just before the traffic lights turn green. It's a handy way to save fuel without dramatically changing driving style or hindering performance. Blue Efficiency B150s and B170s will be available from September 2008.
