If you do a drivers program, and even in some leases, you DON'T have to turn in the car.
If it's a car that has retained it's value very well over the terms of the lease, and the value of the car is higher than the residual, you can just sell the car and pocket difference.
In a drivers program you have 4 options:
1) pay off the residual and keep the car
2) finance the remaining residual balance and keep the car after your financing is done
3) turn the car in to the dealer (or bank)
4) sell the car yourself and pocket any profit
Option 3 is the most commonly used, and 4 is the best route to go if you can.
If you got a nice car like a Toyota, Honda, or Subaru that retained it's value very well over the 2 or 3 years of the lease, you might come out ahead.
I was looking into a drivers program on a Subaru WRX wagon. I would have don it for 3 years, 10,000 miles and they were telling me that a 3 year old WRX with 30,000 miles would have only been worth $14,000. I think that whoever who made up those numbers is smoking crack. I think the WRX's will maintain their value VERY well.