We could just wipe this debate out right here and say buy the Electric Drive B-Class – you’ll pay somewhere in the region of £2 for every 100-miles you drive (an utterly unbeatable cost-per-mile ratio compared to petrol or diesel) and you’ll never have to pay any road tax. Of course, there’s a catch and it’s the Electric Drive’s limited 124-mile range, so it won’t be suitable for all.

While there are no current B-Class models that dip into the sub-100g/km free road tax bracket, all of the diesel models are in Band B, so will cost you just £20 a year to tax, with the exception of the B220 CDI 4MATIC four-wheel-drive model, which has 130g/km CO2 emissions so costs £110 to tax for a year.

Mercedes B220 CDI 4MATIC Sport - front tracking

.imgHideOnJavaScriptDisabled_40599x15mohrmoae { display: none !important; }

While fuel economy claims should always be taken with a pinch of salt, both the B180 CDI and B200 CDI say they can beat 70mpg when fitted with Merc’s 7G-TRONIC automatic gearbox, and experience tells us they’re not fibbing – at least 60mpg is possible with a diesel B-Class in daily driving.

The petrol models fare unsurprisingly less well, but they’re not entirely outclassed. Both B180 and B200 claim better than 50mpg on average (mid-forties is probably about right) and given that they save you a considerable amount of cash at purchase time compared to a diesel, they can readily absorb the extra costs of tax and fuel.

Insurance groups

The lowest rated model is a B180 CDI SE which sits in Group 12 for insurance, while a a B220 CDI 4MATIC sits in Group 27. Electric Drive models sit in Groups 24 and 25.

Depreciation

While you might expect any car with a Mercedes badge to hold back the hordes of depreciation, it’s not quite the case – the B-Class doesn’t beat the benchmark 50 per cent retained value after three years (a £22k B180 will be worth roughly £9k after three years) so it’s no better off than its more mass-market rivals. It’s also a car with a long, sometimes bewildering options list so choose your spec carefully to avoid paying for toys that won’t add value come resale time.