I would be inclined to simply put a battery in it and try to start it. Depending on how much gas is in the tank and the conditions it has experienced it might just fire up.

Make sure you have some indication of braking power by seeing if the correct pedal is there.

If it starts let it idle (if it will) or at least keep the rpm's low. Watch the temperature gauge. Once you see some movement there slip it into gear without applying throttle and let the juices circulate. Move from Drive to Reverse (assuming automatic)and allow things to get pumped up.

Carefully allow the car to move and check if the brakes will actually stop the car. Check lights and signals and drive on home.

More often than not I have found that cars that have been sitting for quite some time will start and run without much effort. That does not stop me from using fuel stabilizer in my seasonal storage cars but you might be surprised how long a car can sit without ill effects.

I would not wait long to top up the tank with fresh gas after starting the car. Perhaps the owner was forward thinking enough to eliminate as much air space as possible by filling up before parking the car.

I do not use dry gas in cars with fuel injection but in this case I would not hesitate to add a bottle or two to deal with any condensation that may have pooled in the bottom of the tank.

Good luck and let us know how it does.

Randy