this is nightline, october 4th, 2012. good evening, i m terry moran. well, tonight, there may be a secret cash cow parked in your driveway. because that old car may actually be worth thousands of dollars more than you think. when it comes to selling your own car, some quick, easy, do it yourself tips could help you increase the price, and there s a lot more to it than just hanging up a gas station air freshener in there. abc s sharyn alfonsi brings us the best strategy for selling your old wheels. reporter: meet the gross family. brian, his wife lauren, dog layla and that s their baby, who often gets into the car through the trunk. doesn t take long to figure out why they need to sell their car. it s a disaster. reporter: so, if your wife wanted to get in here she would have to sit like this, right? she would have to be, like, in the fetal position. the blue book value for the car is $9,000, but a local car dealer offered him four. he thinks it s worth more. so, bri