Notes:
1. Most vehicles with electric locks still have manual levers to unlock the doors in case of a power problem (getting locked IN your car because of a blown fuse is a much bigger problem than not being able to get the window up or down). In most cases, power locks and windows will continue to function even if the vehicle is totally submerged.
2. ALL 4-door cars and trucks sold in the U.S. since about 1990 or so have locking mechanisms located on the (for lack of a better term) rear door jam (on the door itself), below the latch that, if set, prevents the door from being opened from the inside, to keep small children from opening the back doors while the vehicle is in motion. Something to remember.
3. All cars with separate trunks sold in the U.S. since 2001 have a "glow-in-the-dark" release handle in the trunk, so that a person locked in the trunk can get themselves out.
4. In the case of a water immersion situation, your best bet is to get the windows down or out and exit the vehicle through the window opening. The doors are almost impossible to open after the water rises only about 6 inches above the bottom of the door (and will continue to be until the vehicle is full of water). Those "little hammers" (with the pointed end) they sell for the purpose of breaking vehicle windows do a much job than conventional hammers because the side and back glass is tempered (a fact that surprised the heck out of Adam on 'Mythbusters'). Forget about breaking out the windshield, it's laminated.
JimJr