My car lease allows me 15,000 miles a year -- but last year I drove 65,000. What can I do to avoid the fee?

You're right about one thing: The best way to avoid some truly nasty overmileage charges might be to buy the car outright. But buying it today — or anytime before the lease is up — isn't the way to go. To get the best deal, you'll have to wait until the lease expires.

Folks who purchase their leased cars once their lease contract expires aren't subject to any overmileage charges for going over their mileage limits, explains Tarry Shebesta, president of LeaseCompare.com, an online lease marketplace where shoppers can get quotes from multiple lenders. In your case, that will most likely save you a bundle. Lease companies typically charge 15 cents for each over-the-limit mile. So if you keep going at your current pace, you'll owe something like $30,000 when the lease expires in three years.

So why not just buy the car now? While this is an option, it's not terribly attractive. To start with, the buyout price that the leasing company will quote you with three years left on the lease would most likely be higher than the car's current market value, according to Shebesta. (Edmunds.com's True Market Value used car appraiser will give you an idea of how much your car is worth right now.) Then there are the various early-termination penalties and administrative fees that could add up to the equivalent of three or more extra monthly payments. (The formula used to calculate those will vary depending on your lessor and is probably disclosed on the back of your contract.) And don't even think about negotiating. "As soon as you show interest in buying the car, you limit your negotiation power," Shebesta says.

Alternatively, if you stay in the lease, your monthly payments and residual value will remain the same, regardless of your mileage. "You are guaranteed to buy the lease car for the residual figure," says Philip Reed, an automotive expert with auto Web site Edmunds.com and author of the book "Strategies for Smart Car Buyers." With a bit of negotiating, you might even be able to buy the car for less. You'll also keep your gap insurance, which covers the remaining of your lease payments if you wreck the car in an accident and are unable to drive it.

The bad news is that if you continue to put loads of miles on the car, it probably won't be worth the residual value price when the lease is up. So if your family emergency continues for the next few years, there's the very real possibility that you'd have to pay more for the car than its appraisal value.

That said, negotiating is always a possibility. Remember, leasing companies don't want leased cars back in their lots after leases expire. When that happens, they're stuck paying for repairs, marketing and shipping the cars to auction sites where they can be sold. They would much rather have you keep the car; in fact, they're likely to start calling you toward the end of the lease to gauge your interest in doing so.

That's the time to negotiate. "They may offer you a very attractive pay-out," Shebesta says. The key is to show as little interest in the car as possible. "You don't want to look aggressive, like you want to buy the car," he says. "You have to play a little hard-to-get on this."

And do yourself a favor: Don't mention the mileage. "If you let the leasing company know that you're over miles as you're getting ready to turn the car back in, they know they've got you over a barrel," Reed says. "You don't have to tell them how many miles are on it. Or at least, it's good not to volunteer it."