We do tend to forget about petrol power for family cars in this CO2-obsessed world, but the B180 petrol is actually a surprisingly sweet little engine to drive, and with care you can stretch fuel economy well into the high-forties-mpg.

• Exclusive images of the 2019 Mercedes B-Class

The only kicker is that with Co2 emissions of 129g/km, you’re going to have to spend £110 a year to tax it, whereas an equivalent B180 CDI diesel will cost you just £20 per annum. In overall performance terms, the sweet spot is the 2.1-litre four-cylinder B200 CDI diesel, with 134bhp and a helpful 300Nm of torque. It’s also a Mercedes-built engine, whereas the B180 CDI is actually a 1.5-litre unit borrowed from Renault-Nissan. Perhaps that’s unimportant, but it may matter to some.

Mercedes B220 CDI 4MATIC Sport - cornering

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If you’re willing to look beyond these most popular versions, there are a couple of left-field B-Classes that are worth a look. The B-Class Electric Drive uses a 176bhp electric motor fed by a stack of lithium ion batteries to produce a brisk 7.9sec 0-62mph time, and a claimed one-charge range of 124-miles. Think of it as a more conventional rival to the groovier BMW i3 - though it's not nearly as good to drive nor as pleasant inside.

Surprisingly the fastest petrol engine, the B200 turbo, is actually nearly half a second slower to 62mph than the electric one, but at least it will still be going at mile-125. With 154bhp and 250Nm on tap, it’s a decently brisk motor and costs just £20 a year more to insure than the more basic B180 petrol.

Mercedes B220 CDI 4MATIC Sport - rear tracking

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It’s actually a rather sharp car to drive too. True enough, the steering feel and weight could be a little more consistent, but overall, and especially for such a tall vehicle, the B-Class feels good through the corners and the ride quality is exceptionally good, especially if you avoid the 20mm-lower AMG suspension option.

Engines

It’s a pretty simple choice when it comes to picking a B-Class engine. Lots of long motorway miles to drive? Go for the B200 CDI, which should manage better than 65mpg on a long run. Are urban journeys more your thing? Then the B180 with 120hp should do the job – you’ll keep at least £1,000 to spend on fuel, compared to the cheapest diesel and it’s a smooth and refined engine.