Isn't there several different lease contracts you can get into? Giving you several different ways to end the contract, depending on if you think you'll buy it, or trade it? A friend of mine was able to extend the lease on his Jeep Grand Cherokee for instance.

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past MB rides:
'68 220D
'68 220D(another one)
'67 230
'84 SD
Current rides:
'06 Lexus RX330
'93 Ford F-250
'96 Corvette
'99 Polaris 700 RMK sled
2011 Polaris Assault
'86 Yamaha TT350(good 'ol thumper)