Leisure Suit Larry: Box Office Bust
30 Achievements
PS3
Le Manns
Drive in vehicles for a total of 3 hours while playing the game
10.2%
How to unlock the Le Manns achievement in Leisure Suit Larry: Box Office Bust - Definitive Guide
I think you need to make sure you are in the driver's seat and not the passenger's seat (if you take over someone's ride). True that you should get this through normal play but if you just want to knock out an easy achievement, do as Zinadine76 said. If you don't use a wired controller or charge-n-play cord then the game will pause (stop the time) when the controller goes off.
Ok you can do this while playing the game normally or use the following method which i used. This game is so bad i played it for around 5 hrs before taking it back so i plugged in the charge kit (to stop the controller going off) and simply got into a golf kart and then went and had my lunch and watched a movie. The achievement will pop up after 3hrs even if your sitting stationary in the kart.
This should come automatically without you knowing it. You will rack up the minutes when completing the game, when completing all races see Pedal to the Metal and when trying to reach the 400 miles for that trophy see Road Tripping.
Another way someone said do it is by sitting in the car and leaving your playstation on for however long it takes.