2012 Mercedes B-Class review, road test

The engine in the B180 is from an all-new engine family (engine code: M270). It’s an all-aluminium 1.6-litre turbocharged, direct-injection petrol engine that sits transversely over the front axle. The direct-injection system runs a pressure of 200bar and uses piezo injectors that handle upto five injections per cycle. The engine weighs just 137kg and part of this weight saving is down to the hollow crankshaft.

The B-class always starts in Eco mode, and that means the seven-speed auto upshifts early and the quick-acting stop-start system is eager to cut in every time you come to a stop at a red light.

To get the best out of the engine, you need to switch Eco mode off, put the transmission in manual mode and use the well-finished paddles behind the steering wheel. Do so and it will hit 100kph in 10.2sec and will go on to a top speed of 192kph – very impressive figures for a car that weighs over 1.4 tonnes and makes a modest 121bhp.

Around town, the engine is smooth and adequately responsive. The specs say the peak torque of 20.39kgm kicks in at 1250rpm, but the real grunt is only when the engine is spinning closer to 3000rpm. In fact, the mid-range is particularly punchy and the engine pulls strongly all the way to 5000rpm. Rev it past this and it does get a tad vocal, and it isn’t particularly enthusiastic near its 6300rpm redline. You sometimes wish it had a little more low-rev grunt – the transmission doesn’t downshift readily and you have to occasionally force it to do so by hitting the kickdown switch.

This being a Merc, the seven-speed, twin-clutch gearbox doesn’t have the jerkiness usually associated with this kind of transmission. Set the gearbox in Economy mode and it will shift up smoothly and early in the rev range, and will mostly disobey commands from the paddle-shifters. In Sport and Manual modes you get more control through the paddles and it’s fairly responsive and quick acting.

The B-class is a pretty good cruiser too and, again, there’s always sufficient grunt for highway duties. Overtaking is quite easy thanks to the strong mid-range and this makes the B 180 feel even quicker than it actually is.

Fuel Economy

The B-class’ quick-to-cut-in stop-start function and Eco mode help its fuel economy in the city. We got an absolutely decent 9.5kpl. Its slippery shape and low drag coefficient helped it return 14.2kpl on the highway.