Is My Vehicle in Danger of Sinking if Water Enters?

[AnonyMous2014]

I need to know approximately what percentage of a vehicle with an airtight passenger compartment must be filled with water before it sinks to the bottom.
The fact that it is airtight may normally prevent it from sinking, but if a window was cracked from impact, and water slowly trickled in, would that be enough to make a car sink?
Also, would the car sink nose-first if it fell from an elevated surface on its side?

 

[phinds]

I need to know approximately what percentage of a vehicle with an airtight passenger compartment must be filled with water before it sinks to the bottom.

Well, let's see. Suppose the vehicle weighs 10 tons and the compartment is 10 cubic feet. You get one answer. Suppose the vehicle weighs 2 tons and the compartment is 10 cubic feet. You get a very different answer. You see how an ill-specified question can basically have no meaningful answer ?

 

[davenn]

Also, would the car sink nose-first if it fell from an elevated surface on its side?

if the engine was in the front, then probably, yes