Killing a fleeing enemy

[Lord Kira]

   I have sort of a situation specific question here, Last night I was in a warthog as the gunner myself and an enemy hogs gunner both attacked and killed the others driver. After we were both thrown from our hogs I saw he was going to drive off and I stuck his hog with a plasma as he began driving killing him in the process. Right after I got in my hog and proceed to the next nav. Not sure if me killing him in that situation was against the rules so I figured I'd ask for future reference.

[BFM_Exodus]

Although what you describe Lord Kira is not against the rules, I would discourage doing it in the future. Obviously the aim of the game is race, and you both had a hog. It is more admirable racing if you drive away with the hog you have, and he drives away in his. Race is always cleaner with each grenade you take out of the equation.