Don't veer out of your path (which, as covered elsewhere, should be to your next flag) to run over an opponent. This is called chase killing.
You may, however, run over an opponent if they pose an immediate threat. For example, if you are solo in a hog, and an enemy is about to get into, or is in, the gunner's turret of a hog, you may swerve to kill him or knock him out of the hog.
Do not stop or slow your hog, or otherwise delay your hog's progress, including by spinning, for the purpose of allowing your gunner to fire at an opponent.
You may choose a route that maximizes your chance of killing the opponent, as long as the route can reasonably be considered as progressing to your next flag. For example, if a lone hog on the bottom level of Gephyrophobia uses the tunnel to red base to proceed to the top level, a hog with gunner may also go in that direction, so long as they need the lap flag next. (Associated post)
~ No camping or sniping on Race servers
~ Respect the admins & all players
~ No profanity
~ No team nading/rocketing
Most of the rules are pretty easy to follow, but camping can have different meanings to different people. So here is the rule about camping:
Camping is defined as sitting and waiting in a hog, on foot, etc. for the intent of killing another player. If your life isnt in danger on a Race map you should be driving. If you have to stop to shoot to save your life this isnt considered camping.