Re: Why on cold mornings do I see steamy exhaust from my car

Ed,

Water and carbon dioxide are the main products in the combustion of hydrocarbons (gasoline). 
At engine temperatures the water is in the form of steam (an invisible gas) as it passes through 
the exhaust. Initially, as you have observed, the steam cools enough to condense and form a 
"cloud" that you identified as "steamy exhaust". Once the cloud is away from the car, its little 
water dropplets evaporate into the surounding air and again are invisible as molecules. 

By the time the exhaust system has heated up, the water is too hot to condense in or close to the 
tail pipe. By the time it does cool, by collisions with the air molecules, it is too dispersed to 
condense; and it is again just part of the water vapor in the atmosphere.

G.L. Ewald