Is a 4.4imuch more expensive to run than a 3.0i

[X5Jay]

Has anyone tested out what the optimal speed is in top gear for the best mileage? Is it around the 55mph mark or the 90mph mark for example? I suppose this could be done by setting the cruise at various speeds on a nice, long, straight highway with little traffic and resetting the MPG calculation at various speeds. Sounds like a fun task. I'll try it some time when I get a chance, but if anyone would like to beat me to it, it would make for an interesting read...

And one more note, when you're stopped and idling, why does the MPG gauge on the dash read max MPG when it should read min MPG? If you're not going anywhere with the engine running, you are getting 0 miles to the gallon. I'm assuming it's because the gauge runs off engine vacuum and it's just not that sophisticated...

[DinanX5]

Originally Posted by X5Jay

Has anyone tested out what the optimal speed is in top gear for the best mileage? Is it around the 55mph mark or the 90mph mark for example?...

I once read that the optimal speed for gas mileage in cars was 47.something... I imagine that it would vary depending on several factors (C of Drag, mass, etc.) but it's probably in that neighborhood for all vehicles.

[phil47]

Assuming that instantaneous fuel economy gauge on the cluster is relatively accurate, you should be able to figure it out fairly quickly. Start at 40 mph on a flat stretch (cruise control on), and increase in 5 mph increments while checking approximate fuel economy. You'll probably find a sweet spot...I'm going to try next time.

[somewhereinla]

The 4.4 is a newer design than the 3.0 which incorporate new, more efficient technologies, like valvetronic. The 3.0 is a much older design which is being replaced(new 3 and 5 have it) but not on the x5 yet. And by the way, the 3.0 is not a V6 but an inline 6.

[YankeeBimmer]

I have a 4.4 and you will pay dearly for the gas!

[phil47]

I have a 2005 4.4, and I don't care what you drive...if you have a heavy foot around town you will pay!

I usually pull off around 16 MPG in town, but this thing is great on the highway. I am getting 26 MPG by driving steady around 60 mph...and this thing isn't even broken in yet.

[drex]

it will be if Rita hits the Texas coast..

[pepatrick]

My 2001 4.4i averaged .5 mpg better than my 2001 3.0i. I suspect that my 4.6is will not do better...because it will be way too much fun to drive at full throttle.

[robocal]

Thanks for the replies..very interesting. Just for reference most of the X5s I'm looking at are 2001-2003.

I notice some of you talking about valvetronic technology but am I right in saying that this was not available on the older X5s ?

Also where I live there is not going to be a lot of highway driving mainly city driving so in that case would the 3.0i not be better with a smaller engine capacity ?

Pepatrick I was especially interested in your posting. Presumably you drove both the 3.0I and the 4.4 in the same style ?

Also what about servicing costs are they appreciably more with the 4.4i ?

Finally what is the conversion rate between the US gallon and the imperial gallon ? Presumabley most of you guys being in the US are basing your figures on US gallons.

[somewhereinla]

the 4.4 engine in the 00,01,02,03 is a completely different 4.4 engine than the 04,05,06 and the older was not valetronic.