2006 MCS/auto

So I have the common fuel sender issue, where from full to 2/3 full, my fuel gauge is erratic - either pegged at empty or totally full. I know it's the passenger side fuel sending unit, and I know I need to replace it. But here's what mystified me on this tank of fuel:

The gas gauge acted just as it should with this issue, pegged at empty until a couple miles had been put on there, and then it showed fuel. Here's the kicker though - I had only put 10mi on this last tank, and the range showed 260 miles. Normally, my MINI goes maybe 300-330 miles per tank.

I actually attributed the incorrect range to the erratic sending unit, until last night, when upon refueling, I noted that I did 220.9 miles in 12.56 gallons. That's right folks, a whopping 17.58MPG. To that I have to say WTF?!

I romped on it a little bit this last tank, but I have never got under 20MPG average per tank before this! I really need some help with this; is there anything I can do to fix my MPG?

Also, as an aside, does anyone have a part number on the fuel sending unit for the passenger side? Thanks!

 

To get the PN# go to www.realoem.com