The plug-in hybrid version. It’s a four-cylinder petrol engine and an electric motor. Both send power, separately or independently, through the automatic transmission. There was one of these in the old 3 Series range, but the new one can go half as far again on electric-only. E-range is 35 miles WLTP. It has 113bhp in that mode, which is enough for most reasonably gentle driving.When petrol and electric are shoving as a team, you’ve got 252bhp. If that’s not enough, there’s a battery-depleting mode giving 292bhp, and a 0-62mph time of 5.9sec. To summon this, you press a button labelled XtraBoost. Seriously. How very Buzz Lightyear.An obscure and compromised version of the 3 Series, or the sweet spot of the whole range?Not obscure. The 330e will be among the biggest-sellers – likely to be one in four of all 3 Series sales in the UK. And this time around they re-engineered the location of the battery, so that they can do a folding rear seat. Which means there’ll also be a Touring. Look at the CO2 figure and you’ll see why the 330e will be popular.