Let's face it - we didn't buy them for their fuel economy. In the UK most E53 X5s are 3.0 Diesel! I chose to buy a 4.4 as I don't do a huge number of miles (and I like the sound of a V8). You guys in the USA are very lucky anyway - petrol prices (sorry - gas to you) here are well over £5 ( $7-50 ish) a gallon!