What APT said is right on. NEVER willingly lease a car knowing that you will be going way past the mileage limits. It's ALWAYS cheaper to boost up the mileage as part of the lease agreement, in many cases you'll only pay 10 cents per mile (sometimes a bit more, sometimes a bit less - depends on the manufacturer, the vehicle being leased, etc.) ahead of time instead of 15-20 cents per mile penalty rates after the fact. As much as you may think you can predict the future, you never can, and as much as you might think you'll be able to buy the car outright in four years, you never really know what situation you'll find yourself in four years from now. At the very least, build the miles into the lease agreement, that way the residual value of the car at lease termination is such that you have the option to hand the car in with no penalties or buy it for somewhere around what it's actually worth. You don't want to shanghai yourself with only bad options when your lease period is up, I've seen too many people do this. A great example is a buddy of mine just handed in his G35 sedan that he leased. He leased a new Infinity FX35, which had a lease deal for around 400/month, but because he was way over the mileage on his G35 lease and he terminated the lease six months early, he's paying 600/month on the Infinity. So, effectively, he's paying an extra 200/month for a car (the G35) he no longer gets to drive, for the next 48 months. When you think about, that really sucks big time.
I lease my Alty SE-R because I know I want to drive a new vehicle every three years and because I write it off against a side business to boot. I only drive about 10k miles per year because I use public transportation to get back and forth to my job for the most part. I leased with 12k/year giving myself roughly a 20% buffer, which is another thing I recommend, give yourself buffer room in the mileage. If you come in under your mileage dealerships love that, and will oftentimes give you another sweet lease deal on your next car because they have wiggle room because they're going to make a good chunk of $$$ on your lease trade-in on the used lot. I've even seen dealers waive a large part of lease downpayments in these situations when someone is handing in a really well cared for leased car that is under the mileage by 20%.
