Yup, all sounds logical. You've educated me here. Before I knew some of the disadvantages to buying a diesel if you only do 12,000 or so per year. Such as: diesel is more expensive than petrol, expensive glow-plug type things and the like. I worked out that you'd have to do 20,000 miles per year before it benefits. Not to mention all that rattly noise you have to tolerate. I wasn't aware of some of the other things you've mentioned though.
I've known two people who bought small diesel cars (one a Citroen, the other a Peugeot) because they thought they would save money. At the time, I said to them both: 'You only do 10k a year, it's not worth the extra price of diesel and the extra price of those components that pack up, which they will.' Both these girls sold a Vauxhall Corsa and a Ford Fiesta to buy these same year diesels. Within six months they were both complaining about expensive things that packed up. Oh, both were only doing short school type runs and round town stuff. Lady with the Peugeot had to spend £175 on, can't remember exact name for it, but a glow plug thing? not once, but four times during the first four months, £700. I figured if that was a petrol car it would have been four spark plugs at £3.00 each. Basically, that £700 killed any petrol saving for the next 20K, probably two years the way she drives, and that's if she had no more problems over that two years, which she did, big time. Both these girls did, big time. But, they persisted and kept on spraying the money hose at these stupid cars. Fact is, it was penny pinching. Going from a 1.3 fiesta petrol to a 1.6 Peugeot diesel was a stupid thing to do. Oh yes, the used diesel car she bought cost her £1,500 more after she trading in her petrol. Add that to the £700 and we were up to £2,200. Plus she had about £800 of other diesel related crap go wrong with the car, so about £3,000 in total. I figured she'd have to do 60,000 miles in that car just to break even. By then, the silly little engine and gear box would be about ready to give up the ghost anyway. Point is, I'm just telling you this little story to let you know that yes, it does sound logical to me, but then, I'm quite an intelligent guy. Also, one small thing, in the UK, the government could quiet possibly f••k us all in the a••s for owning a diesel if they decide to hit the 'city tax' thing with diesel owners in this country. So many reasons to have petrol. Shame there is so little choice though with a 7 series. But, if I keep my options open and go for a 6 or a 7, which ever comes up and looks like a deal first, I could be in.