I had an E53, and enjoyed it, but when it came time to replace it I wanted more handling performance, without having to pay to keep a Z4 in the garage for sunny days. The E70 design went the wrong way IMO, as it was larger and heavier than the E53. I went for the E60 535i, and am very happy with it. Mine has a manual transmission, M Sport package (which is what the last 550 had as standard), better fuel consumption, and far better handling. The X5 has great handling for an SUV, but a car will beat an SUV any time. I didn't want the penalties associated with the 535xi (handling, weight, fuel consumption) so I bought the best snow tires I could for regular winter trips through the mountains. The 535 rwd with Dunlop Wintersport M3 tires did better in winter conditions than our X3 with Pirelli Scorpions (not the dedicated Ice version).

I don't need a new 5 series, but I really like what they have done with it. Mine would be a 535, not a 550, though.

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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