There is an age dependent tapering VRT rebate on plug-ins that makes them attractive. The depreciation code being used (and low CO2 and NOx) for them at the moment means that VRT is pretty low, so it makes them attractive as an import. To compare, a 2016 330e M-Sport with a similar 320d/320i, the combined VRT and NOx levy comparison is ~€1200 vs. >€4000. As a result, despite the used 330e being more expensive than either the 320d/320i in the UK, the on-the-road price is roughly the same. I'd imagine that over the medium term the residual value of a 330e will exceed a 320d or 320i, especially the 320d.