What could be the problem when a car's exhaust emits thick, light-coloured smoke? This usually happens when my car's engine starts up again after a long drive on the highway several hours earlier.
Usually, this is caused by condensation forming in the exhaust system.
The exhaust system heats up when the car is driven for a long period and/or at highway speeds. When it shuts down and the exhaust cools down, moisture from the air condenses and collects inside the exhaust.
When you drive the car again, the moisture in the exhaust is turned into steam. Sometimes, water even drips from the end of the tailpipe. This is usually much easier to see on a cold day.
AUTOMOBILE ASSOCIATION OF SINGAPORE