I seem to have a lot of water condensation coming from 6 inches behind my tailpipe after short trips. I actually have water dripping up my driveway and pooling in my garage. Is this normal or should I have checked out?
I remember from Chemistry that water is one of the normal products of combustion of hydrocarbons (burn any hydrocarbon and you get H20, CO, CO2, etc.). The amount of water depends on the reactants - in this case gasoline. Gasoline is actually a blend of hydrocarbons so it's hard to say exactly how much water should be produced.
I think the key factor though is the ambient temperature outside when you're noticing the puddles. Personally, I wouldn't worry about it too much if the air is cool outside - there's a lot of water vapor released during combustion that you normally don't see, but when it's cool outside the air can't hold as much water so you see the condensation. Also, the cement floor in the garage is probably cooler than the air as well so the water condenses there just like it does on the outside of a soda can in the summer. I suppose the same is also true if you're in a very humid climate - if the air can't hold any more water than it already has in it I wouldn't be surprised to see some precipitation/puddles.
Sorry, not very helpful but personally I wouldn't worry too much. While water can be indicitive of incomplete combustion which may mean something is wrong with the injection system or engine - I'd bet you'd get a "service engine soon" message if something was awry (I'd sure think with all the sensors in cars now days that something like that would be monitored.)