If there was a E70 diesel available I wouldn't hesitate a second to get one, well of course with reasonable price. I've driven both ML 320 CDI and E53 X5 3.0D and they have a lot better performance than any 3.0i and I don't believe 3.0si can meet it either. And by performance I mean every day driving on FW, how fast the car accelerates from e.g. 40 to 70 and how strong it is towing a trailer. But yes, by comparing only the gas vs diesel price and costs per year it doesn't make sense to buy a diesel... but, the torque of diesel