My understanding is that lease rates aren't published in advance. Since the M5 is not in the US market yet, they can't price out a lease for you. If you order an M5 for delivery in August, then they will finalize your lease payment when the August residual and money factors are released on the 1st of the month. If you were ordering a car that is already in the US market (i.e. 550), then they can use current month's lease rates for a future delivery. In this situation, you get the benefit of cherry picking the best lease rates up until the time you take delivery.
Have you considered financing? I'm always a fan of leasing except when the car will be in high demand and it will have limited supply. I'm guessing the lease rates for the M5 will be ugly and your monthly payment might be similar to a finance payment over 60-72 months.
'14 M5 CP
Black Sapphire | Black | Executive | Lighting | B&O | Exhaust Meister | 35% Llumar tint | Passport 9500ix
'13 X5 50i M Sport
Carbon Black | Black | M Perf | 20" 333M | Lux Seat | Active | Adaptive | Cold | Tech | Sound | Prem 2 | Apps
Black kidneys | 35% Llumar tint | Passport 9500ix
'12 550xi, '11 335xis, '11 X5 50i, '08 BMW 535i, '08 BMW 335xic, '05 Audi S4, '02 Audi TT Coupe