If you can swing the payments without selling any stock, then that's the way to go. Stocks will generally appreciate (assuming you plan to hold on to them for a long term), while a new car will always depreciate.
Leasing is generally a bad idea if you plan to own the car. If you buy the car at the end of the lease, you would pay the pre-determined residual value (what the contract says the car will be worth at the end of the lease). In recent years, this has been higher than the actual market value, which means it wouldn't be a good decision (although this is changing now). Plus, you're already into the car for the amount of all the lease payments plus interest. When you add all this up, it very rarely makes financial sense to lease a car if you plan to eventually own it.
With 0% financing, it may actually be cheaper to buy a new car vs. a used one. Figure out what the total (with interest) payments would be at the end of a used car loan (the loan officer will be able to tell you this, or you can use an online calculator) and compare it to a no-interest new car loan. Keep in mind that most if not all of the 0% deals are for 36 mo. financing, which most people can't swing. There's also usually a minimum down payment for these deals.
If you cant find an MP3, check out the Protege 5. I drove one for a day and was very impressed. The V-Spec also seems like a great car, but I haven't driven one. Could you wait for a Focus SVT? If not, check out the regular ZX3... it's probably the best bargain out there right now.
Just my $0.02.
