Ignore the model nomenclature, as the numbers on the rear hatch have no bearing on the engine size. All are turbocharged four-cylinder units. The B 180 and B 200 use the same base 1.6-litre petrol engine, producing 120bhp/147lb ft and 154bhp/184lb ft respectively. They're not fast cars, but at least that torque is available across a wide rev band.
Meanwhile, the B 180d uses a 1.5-litre diesel engine putting out 107bhp and 192lb ft, which feels faster than you'd think because of that torque figure and the fact it's lighter than the other diesel models. They're made up of the B 200d and B 220d, sharing a 2.1-litre four-cylinder unit that produces either 134bhp and 221lb ft or 174bhp and 258lb ft.
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The B 220d is the only B-class offered to British buyers with 4Matic four-wheel drive - useful for those living in hilly areas come winter time, but not of mass-market appeal because of its extra cost and fuel consumption. Indeed, while all other examples of the B-Class come as standard with a six-speed manual gearbox (and the seven-speed dual-clutch auto as an option), the B 200d and B 220d can only be had in automatic guise.
Then there's the B 250e, which doesn't have anything like a 2.5-litre engine as its name suggests, as it's powered by electricity. An electric motor serves the front wheels and there's a 28 kWh battery pack mounted low in the chassis. As we've come to expect from electric vehicles, it majors on torque - 250lb ft delivered almost instantly, but power is respectable too at 177bhp.