I'd be inclined to go for petrol too, despite your use being motorway based.

The tax situation is nigh on impossible to guess, either way there seems to be no shortage of buyers for used German prestige marques so it's not as if you're going to get stuck with a car the depreciation of which will break you, some people will always prefer one fuel over the other and are prepared to pay the costs involved, espcially if it's up the range which is where you are heading.

Enjoy whatever you choose.

the dealer I test drove the cars with said he couldnt remember the last time he sold a 328i, said he sold the odd 335 but otherwise it was still diesel, diesel, diesel.

That's as much to do with BiK as anything else i would think, i wonder how many companies have a Diesel and hybrid policy only...thinking about it our company cars right up to MD level are one or the other, mind you the chairman has whatever takes his whismy and can't say i blame him.

Do you want M sport spec with presumably a harder ride and huge wheels?, if so by all means have it but i wouldn't be too sure that every used buyer will be thinking along the same lines, seems a shame to buy something you don't actually want purely to make it saleable to a possible market sector in due course, but if you want that spec its your money and only your choice and thats how it should be.

As for BMW sales bods, hope he's sharper than the one who told a chap i know, who happens to own half the village where he lives, to come back when he could afford one when he went in dressed in his normal casual/scruffy style...had super salesman looked at the number plate on the common or garden car he arrived in he'd have seen one relating to his profession worth around the price of a new 7 series.