You can pay multiple security deposits to lower your money factor. BMW holds them and returns them once the lease it completed.

I think BMW allows up to 7 security deposits to be made, each will lower the money factor .00007. So all 7 would drop it .00049 or around 1.2%.

You can calculate your rate of return since the 1.2% applies to the entire lease, where the multiple security deposits interest lost (so to speak) is only on that. So if your payment was $800, you would give them $5600 for seven deposits. You only lose return on your $5600 for three years, but gain 1.2% off the depreciation + residual interest.