since delivery I have averaged 9.8 L/100 km and thats with the odd hammering here and there. Avg speed thus far is 55.7 km/h and consistently getting 830 to 880 kms between fill ups.

On the highway travelling around 110 km/h the consumption gauge hovers around 8 L/100km and cruising at 60 to 70 km/h it gets down to 5 to 6 L/100 km

Certainly a big improvement over the previous X5 diesel and I believe at least 5 L/100 km on average more fuel efficient than the 4.8i.

I know of one 4.8i owner who has similiar average speed to mine (around 55 km/h), drives at mainly highway speeds and averages 15.6 L/100km without hammering.

Go with the 4.8i if you like the sound of a V8 and dont mind the fuel bills.

I wouldn't bother with the 3.0d when the 3.0sd is available. Diesel may cost more than fuel but they run much cooler and at lower rpms than petrols. In my previous BMWs that were petrols I could take a short trip and after coming back, open the bonnet and it would be damn hot under there.

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2008 X5 3.0sd Sports
Space Grey, Camel Leather, Bamboo Trim, 214 alloys

Previous cars
2000 E46 323i Steel Blue
1997 E39 528i Oxford Green
1999 E39 535i Orient Blue
1997 E39 540i Black
2005 A170 Atoll Blue
2005 E90 325i Alpine White
2006 E53 3.0d Sports