I was in the same predicament, best 06 E53 or bottom of the barrel E70?

Chose to go with the best E53, its a nice ride & I'd suggest you just try em out.

Not to discount the E70 at all, I'll be buying one next year.

But bang for buck the 06 E53 is a good value proposition as well as being the best of the generation where as the 07 E70 is the first of the generation.

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2006 E53 Kalahari Beige, X5 3.0d Sport [sold] | MY13 Audi A1 Ambition | 2004 911 GT3| W124 Estate