Key in, clutch down, thumb the starter button and the One’s 1995cc twin-cam four’s refinement is excellent. Second-generation common-rail injection, together with a variable-geometry turbo-charger, help the 118d to produce 122bhp at 4000rpm and 207lb ft at 2000rpm – 41bhp and 44lb ft down on the 120d.
But it remains eager, pulling from as little as 1000rpm, and shoving to 60mph in 10.0sec.
It’s the mid-range performance that feels strongest - stronger on the road than the wind-affected 13.0sec 50-70mph time in sixth suggests. Running from 30-70mph in fourth takes just 4.3sec longer than through the gears.
Under braking the BMW can weave, but the ventilated front and solid rear discs showed no sign of fade, with the 118d coming to rest from 70mph in just 47.8m.
BMW aimed to set new standards with this car’s handling – it has succeeded. The steered wheels are unencumbered by drive, ruling out torquesteer, and weight distribution is near-perfect at 51:49 front-to-rear (the 116i is nearer 50:50).
At low speeds the hydraulic power steering’s heaviness is a surprise, but pick up speed and it’s fluid, perfectly weighted and quick. Combine this with excellent body control and you have a car with real eagerness to change direction.
The 118d is a natural understeerer, and without the torque to induce power oversteer it takes an abrupt release of the throttle during a hard-taken bend to change that.
In the wet it’s more playful, but high grip levels and the standard stability control mean that you’ll be well protected in most circumstances.
BMW’s run-flat commitment is so strong that the 1-series doesn’t even have a spare wheel well. We’ve been unimpressed by the compliance of other run-flat-shod BMWs, but on standard suspension and 16in rims the 118d is the best-riding run-flat-shod BMW we’ve tested.
