Lots of things can happen to a car thats just been sitting for a long time, before you drive it any where be prepared to:
Drain all the gas out, and refill it with freash fuel.
Change the Oil.
Change the Brake Fluid and Clutch Fluid if it has one.
Unsieze/Replace the brakes, very common for them to rust solid.
Be prepared for a number of rubber components to have gone hard as they have dried out, and may start leaking fluids.
If the car was just parked and left, then I wouldn't hold high hopes for it ever being much good again.
If it was preped before being left, then theres no reason you can't get it working properly again, but cars like to be used and looked after, not forgotten about for 18 months.