I've been holding out for the x5 diesel that's supposed to be available in the US in March. However, I'm beginning to wonder if the cost disadvantages of diesel outweigh the mileage advantages over gas. Diesel fuel used to be quite a bit cheaper but here in our part of the SF Bay Area diesel is now $3.69/gal and premium gas $3.59. Gas mileage will be improved on the diesel but with the cost of diesel fuel escalating, I'm wondering what we'll see down the road. With more and more companies bringing diesels to the US, I would guess that diesel fuel will be at more of a premium in price and maybe even in short supply, therefore owning a diesel could be a problem. I can't decide whether to buy another x5 gas guzzler now or wait until spring for the diesel. Are there significant performance factors that make the diesel really worth waiting for in spite of the high fuel costs? Any thoughts?? Thanks.