Tonight we take you on the inside, a revealing look behind the bar, the back room of the supermarket into the parking lot, a ride along with a car thief. Use one of those remote locks, is your car... See More
Tonight we take you on the inside, a revealing look behind the bar, the back room of the supermarket into the parking lot, a ride along with a car thief. Use one of those remote locks, is your car locked after all? Debra roberts tells us tonight, don't be so sure. Reporter: Stealing cars is a blast in grand theft auto 5! So fun, the video game made a billion dollars in its first three days on the market. But in real life -- a car is stolen every 43 seconds, close to a million a year. Steve fuller used to do it all the time. So you were pretty good at what you did? Yes. I've taken a lot of cars. Reporter: With six convictions for stealing cars. Steve says hundreds of other times, he drove off scott free. Okay, so let's be clear. You're not stealing anybody's cars today? I stole cars because I was on drugs and I needed the money. Reporter: Why are you talking to us about it? Because I've changed my life. I'd like to make up for some of the damage I did. Reporter: So tonight steve's going to spill the beans on what thieves know that we don't. Starting with the biggest question -- how do they choose which car to steal? You're basically shopping! Yeah, that's the plan! During the day I would shop and at night I would get the presents. Well, theres lots of nice cars here. Reporter: And what did he consider a nice car? You might be surprised ♪ Reporter: In tv shows like "the sopranos," the bad guys always steal the most expensive cars. In eastern europe you can sell this car for $110-120 thousand, my price to you, $90 grand." Reporter: But in the everyday world of real life car theft -- you got your toyota over here, you got your nissan truck up here. Reporter: -- Your clunker can be just as attractive. Now most people would sort of assume that if it's an older car, you're not interested. That's not true. No the older cars are way easier to take. Reporter: In fact, the top two most stolen cars in 2012? Honda civics and accords, going all the way back to the 90s models! On the other hand, three models of mercedes tied for fewest thefts in the u.S. Last year. Did you almost always score? I'd say a good 90% of the time. Reporter: Steve's favorite location? See, that's perfect right there. A parking garage. Apartment complex means one stop shopping. I can find whatever I need in one location. Reporter: This looks good to you? Yeah. This is nice secluded dark underground spot. This is a candy shop here. Reporter: We set up this garage in l.A. For him to demonstrate. With the help of the sheriff's office we brought in three cars. Then put cameras on steve so we could see what he sees and sent him off. Two cars are locked up tight. But car number one, like many we spotted when driving around has a barely opened window. That's money. That's the easiest. Reporter: It's cracked open maybe an inch, but for steve, that's plenty. A window that has enough room for me to stick my fingers in -- let's get this open. -- I can get out of its track by rocking it back and forth. There. It's out of the track. Pull just hard enough to get my arm down in there, and reach in and unlock it. Reporter: Bingo! In less than seconds. Now for car number two. So what I'm going to do is go ahead and use my tow truck lock out kit. Reporter: What's in a lockout kit? Basically it's a wedge and an air bladder. Slide this air bag in. A few pumps of air. What it's doing is separating the whole door from the body of the vehicle. It's leaving me a gap to put my tool in. Let's take this tool, stick it right in here, like this. Right down to the lock. Now I'm in! Reporter: And he's inside car number two in less than a minute! Now for car number three, his least favorite method. I'd break a window. Reporter: You'd break a window and risk the noise? Break it with what? Would you believe a smashed spark plug? A little piece of porcelain is all it takes, throw the piece of porcelain at the glass. The glass will shatter and it'll stay in one piece. Reporter: So, it's one thing to get in, but you still don't have the key. No. Reporter: So then what do you do? Sometimes, he doesn't have to do anything. Many of us leave keys in obvious places. Ashtray, the door panel, the center column. Reporter: So, we think we're being clever. You're just making it easy for me. Reporter: That's how steve started car number one. There we go, there's the key. Reporter: But here's a scary secret, even if you didn't leave a key in the car, the manufacturer may have put one there anyway. It's called a valet key. A lot of people are not aware that they have a valet key in their vehicle. Reporter: There's a spare key in the car? Yes. Reporter: And you know it but the owner often doesn't? No, they don't. Reporter: For example in some BMWs, THAT VALET KEY IS IN THE Tool kit. For a smart thief, easy pickings, but if he cant find that key -- -- he creates one! I'm trying to thin it out a little bit. Knock the edges down. Reporter: Steve says a filed key can start a lot of cars. He tried one on car number two. I'm jiggling it back and forth in the ignition trying to hit all the tumblers and get them engaged. Its not an exact science. Reporter: But sometimes you put it in the ignition and boom? Yeah. Reporter: You're off and running. And away he goes. Steve doesn't steal cars anymore, but was he kind of the classic car thief? Yeah, absolutely. Reporter: Lt. Jeff enfield, runs a auto theft task force in southern california, focusing on thieves like steve used to be. But increasingly, on high tech modern crooks. Is it harder and harder to stay ahead of the car thieves. Oh, absolutely. We know they're working every day to defeat the next device. A device such as this one, that prevents you from locking your car. Reporter: As the driver gets out he thinks he is automatically locking his car. But lt. Enfield blocks the signal with this small transmitter. If this were real, the doors would remain unlocked. So you may want to click two or three times to be sure. These car thieves, they are computer hackers as well. They're getting into your vehicle, which is a large computer, and they are able to hack into that system and obtain key codes and other information. Here is one way they do that. We plug in the device. Reporter: This little gadget -- we go to the function, program key. Reporter: First it hacks into your car's computer, then it copies the data to start the car electronically and voila. The thief is on his way! This is like something out of james bond! It almost is, isn't it? Reporter: It's crazy. Yeah, it is. We learn things every day from these car thieves out there. Reporter: So what happens to your car after it's been swiped? Welf you're lucky it's just been taken on a quick joyride and you'll get it back. But these days the pros are making the biggest bucks shipping hot wheels overseas, never to be seen again. And of course there's the classic chop shop, where stolen cars get stripped down for parts, where steve used to go. When you would start up a car, and drive off with this stolen car, what was that feeling like? Unfortunately, at the time it was success. I got what I needed to support my addiction. I'm not thinking about, "yeah woo-hoo!" It's just get the vehicle, go.
This transcript has been automatically generated and may not be 100% accurate.