yes - it's mostly the tires. the awd system works well enough, although not as well as Audi's quattro I must say.

I had a 03 4.6is with Pirelli Scorpion Ice and Snows in 265-50-19 size.
Also had a S4 with 235-45-18 Pirelli performance snows.

Both were V8's with 340hp. And even tho the X5 is heavier, the Audi did much better in the snow.

But I had no issue with the X5 at all on those tires, it worked about as good as any SUV I have had with a locked 4x4 configuration. But that Quattro is something else in the snow - step above anything else, IMHO. Well - probably on par with Subaru which is a very similar Torsen 50:50 diff. Mechanical is better than electronic IMO.

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2003 4.6is - SOLD
2003 M5 Imola
2008 Mini Cooper S
2011 Mazda CX9