If you have a car on your property that's been sitting and you have decided to go ahead and sell it, then there are some things you should do. Depending on how long it has been sitting without being started or driven, you need to be careful you don't cause mechanical issues. Before you try to start the car up, that's if the battery is even still good, here are some things you want to do:
Drain and replace the gasoline
You don't want to start up a car that's been sitting for a long time and run all of that old gasoline through the system. The easiest way for you to have the gas drained and replaced is to have a mobile mechanic come out to your home and do it for you. However, you can also purchase a pump system you can use yourself, but they can be a bit confusing if you've never used one or if you aren't a very mechanically inclined person.
Replace the battery
You may as well assume the battery is dead if the car has been sitting for a very long time, and even if it isn't dead, you shouldn't count on it to hold a jump well enough to work each time you go to start the car. The last thing you want to have happen is you go to start the car in front of a buyer and it won't start due to a dead battery.
Replace the tires
When your car has been sitting in the same spot for a long period of time, the tires will take on a certain shape from the weight being put on them in the same way for so long. Not to mention, the tires can get dry rot from having the sun consistently beating on them, and they have probably lost some air, which can weaken them when they sit there like this.
Check under the hood for rodent damage
If you are going to be selling a car that you have left sitting on the side of the house, then you have no idea whether or not rodents or even birds have turned the motor compartment into their home. Look for obvious nests, as well as ripped apart insulation or even damaged wires. If you think animals have been living in the motor section, you need to have a mechanic make sure no electrical damage was done and that all of the hoses and belts are still okay.
For more information, contact a professional in your area like those found at Goose Automotive.