As long as you can suck air in, and blow exhaust out, you can run a diesel engine completely submerged in most cases. The New Jersey National Guard apparently tried to take advantage of this capability, without quite enough common sense on driving through flood water:
If you follow the video through to the end, you’ll see where Chris Christie gets it from. Not too smart, I have to say. But I’ll give them credit for trying.
Hat Tip to WizardPC, who notes that there’s no “S” in HMMWV. Though, I would note those don’t look like hum-vees to me. Still, it’s good that the equipment will still allow our troops to do something that could be necessary at some point, but probably not wise in most conditions.