All you need to know is that a lease is exactly the same thing as buying because you get the purchase option at the end. If you do build up equity at the end of the lease, you can always buy the car and sell it yourself to capture that equity. Leasing companies will all cooperate with you in doing these "third party buyout" transactions.

The only negative for leasing is that you will pay a higher interest rate on the lease than a loan because there are less lease providers than loan providers (less copetition = higher cost to consumer) and the lessor has to be compensated for the risk that the car will be worth less than the buyout price at the end of the lease. Typically, the difference in interest rate is about 2% per annum for the best lease deal on a 911 (at the highest available residual - lower residuals have lower interest rates because there is virtually no risk to the lessor that the car will be worth less than the residual at the end of the lease). Plus, you have to pay an acquisition and disposition fee that together amount to about 1% of the cost of the car. If you think you can invest the differential between the lease payment and the loan payment and the 1% fees and make more than those amounts back, after taxes then you should lease. Of course, the potential tax benefits of leasing may outweigh the additional costs as well.

Not considering the tax benefits of leasing, it turns out that in order to break even, you need to earn about an 11.5% IRR on your money, after-tax, using the 2% differential and 1% fees. That's a pretty steep hurdle for most investors over the long-term. On the other hand, if you can realize the tax benefits of leasing then the hurdle is much lower and leasing may actually be preferable than owning from a financial point of view. That of couse depends on your individual tax situation.

I have an excel spreadsheet that shows how this works (at least in California under our sales tax system). If you send to me you email address in a private message, I will email the spreadsheet to you so you can see how it works.