First, make sure you've got a buddy. This can't be done without two people. It's best to join a squad together and it makes things easier if you both have headsets.

One of you should spawn as an Infantry and the other has to spawn as a Scout.

Find a car, have the Infantryman get in it, but don't drive away yet. Have the Scout place a bunch of charges on the jeep. Have the Infantry player drive off towards a target, such as a base or a tank or a group of enemies.

If you're playing as the Scout and neither of you have a mic then make sure you watch the car at all times, use your rifle scope if necessary. When the car stops at the base or tank, blow the charges. If you both have mics then the Scout won't need to watch the car. The infantry player should tell the Scout to detonate the charges as soon as the infantry gets to the target.

Make sure the Infantry doesn't get out of the car. Because of Friendly Fire rules, neither the Infantryman or the car will be harmed when the charges are detonated. This means that you can bring the car back to the Scout and load it up with more explosives or have the Infantryman repair any damage done by enemies.

This tactic can net you plenty of kills and can make taking down tanks very easy. It can also help make captures much easier.

A car bomb with one person is also useful. Spawn as a scout, put charges on the front of a car and don't switch weapons -- hold the trigger in your hand. Get in the car, drive to a tank or some people, jump out and press the fire button if the car is near an enemy to detonate it.