All you need for this is a digital camera.
Sometime before your event you will need to drive around your community taking pictures of signs. The number of signs used will determine the length of time. Then download the pictures and print them off (4-6 pictures per page). Select any word from each sign and white it out. Then make enough copies for each team and they must drive around town, find the correct sign and fill in the missing word. Have a meeting point arranged and the first team back with the correct words filled in wins.
You can use adult drivers, or come up with an idea for “detering” the youth from speeding. Then have some refreshments to follow.