I am sure the 50i can provide a nice kick in the seat in acceleration, but my philosophy is that if I wanted to drag race, I wouldn't be starting out with an X5 in any case, I would be buying something much lighter. The 35i has plenty of power, the 50i has more. You can tow your fold down fine with a 35i.

If, after your test drive, you were raving about the 50i driving experience, you would have your answer. For the more than $14,000 price premium for two more cylinders, and the 25% higher fuel consumption (BMW figures), I would go with the 35i. BTW, that fuel consumption figure is on the standard test cycle. I suspect that if you use the additional power of the 50i on a regular basis, your fuel consumption results will reflect that use.

Now, how many posts until you get a suggestion to buy the diesel?

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue