If its a modern vehicle, you would be surprised how well they keep water out. On the other hand, I'm very much aware of how deep before my intake goes under. If your vehicle is old enough to have a distributor (mines 1996), there are ways to make them water resistant. I've forded water to the middle of my door in the cruiser and just below the top of my fender in my TJ without problem.
90's and older vehicle's, they mounted the computers a bit low inside the vehicles. Upper 90's they started making the computers water proof and put them in the engine compartment. But only the engine computer. The other computers and connectors in a vehicle are not water proof. You swamp a vehicle, you climb out the window and don't fill the cab with water. This includes new vehicles.
Scott