The Leapmotor B10 is one of those cars that makes you do a bit of mental arithmetic before you’ve even driven it. Not because the range, charging speed or boot space are especially hard to understand, but because the price and kit list don’t quite seem to add up in the usual way. Here is a family-sized electric SUV, with a 67.1kWh battery, rear-wheel drive, up to 270 miles of range, heated and ventilated electric front seats, a heated steering wheel, panoramic glass roof, electric tailgate, 360-degree camera, 12-speaker stereo, 14.6-inch touchscreen, vehicle-to-load capability, 18-inch alloy wheels and a long list of driver assistance systems. And yet, after Leapmotor’s own £1,500 grant, it costs just £29,995. That is the whole point of the B10.…