As far as BMW maintenance costs go, you just pay it up front. Wife's new BMW in 07 cost 3 per cent road tax vs 7.5 per cent sales tax in NC. So paying up front saved some tax for the maintenance.
They also always replace wipers ("at customer request"), despite fact that not always needed.
I had planned to sell/trade it this year to get new warranty; and buyer would still have a year left. But opening new business killed that plan.
Like PerfectLap, plan to keep my Box forever.
Go with Plan C and the Spyder. 
Even if you have to travel to a high volume/high allocation dealer. As I did to get the Box of my choice on the lot.