Fuel sending unit
 

Every time I full tank the car ( I fill it up all the way) the needle on the cluster and on the on board computer stops on 253 mi and slowly goes up as you start driving. The dealer suggested that it was the cluster. The car stayed at the shopps for a month. They said they did several tests to it and that it's fixed. The truth is I full tanked the car yesterday and the same thing happened. Can this be from the fuel sending unit. Is it a hard thing to fix?

I thought I had the same problem. Took it to the dealer and they told me that it was due to the change in fuel , ie, winter grade at the gas stations for the winter months. I am in the Toronto, Canada area. I do not know where you are, but this could be the reason, or as you believe maybe a fuel sender problem.

I had the same problem on the E53 as well everytime I filled up all the way. The needle stayed at where it was before the filled-up and eventually move to full position after going 20 or 30 miles. I never took it to the dealer to see what was wrong since it's a minor problem. To get around that, I turn the key to position 2 then fill up my tank.

I believe the X5 has a saddle-type fuel tank, with a left and right sender for the two halves of the tank. So if you have an indicator issue which shows half-full, and then slowly rises, it sounds like one of the fuel senders is dying and reacting too slow to the fuel level.

I'm not sure if this matters, but my '08 got a recall in the mail for the fuel pump.

-J