Not sure what loan APRs are but these are the base lease rates on the 35i. As you can see, the residual is much higher on the premium and sports activity so avoid the base model for resale value. Don't think there's any reason to wait.

2011 BMW X5 xDrive35i
24 Month – Residual 63% of MSRP – .00220 Base Rate
36 Month – Residual 56% of MSRP – .00220 Base Rate
48 Month – Residual 41% of MSRP – .00240 Base Rate
60 Month – Residual 33% of MSRP – .00240 Base Rate

2011 BMW X5 xDrive35i Premium
24 Month – Residual 67% of MSRP – .00215 Base Rate
36 Month – Residual 60% of MSRP – .00215 Base Rate
48 Month – Residual 43% of MSRP – .00240 Base Rate
60 Month – Residual 35% of MSRP – .00240 Base Rate

2011 BMW X5 xDrive35i Sport Activity
24 Month – Residual 67% of MSRP – .00230 Base Rate
36 Month – Residual 61% of MSRP – .00230 Base Rate
48 Month – Residual 44% of MSRP – .00240 Base Rate
60 Month – Residual 36% of MSRP – .00240 Base Rate

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1995 BMW M3 (Track prepared)
2006 BMW 530xi (Wife)
2011 BMW X5 35d (Tow/Daily)