for me its simple.. I lease a car I want to get rid of in 2-3 years, and I pay cash for a car I'm keeping for 5+.. Both my current cars are purchases, but I did lease a Volvo XC90 recently and that was a great thing since their resale value tanked after the residual was calculated for my lease.

__________________
BMW - X5 4.8i w/all US options packages, 19" Y wheels, White/Tobacco, Huper Optik 50% tint
Mercedes Benz - E320 CDI Park Assist, NAV, Folding Mirrors, Premium Sound, Voice Command, Sunroof, Auto Rear Shade, Bi-Xenon