Final answer:
Applying carburetor heat during engine operation can lead to decreased engine performance and increased fuel consumption.
Step-by-step explanation:
In a car engine, applying carburetor heat can lead to decreased engine performance and increased fuel consumption.
When carburetor heat is applied, it heats the incoming air-fuel mixture. This can cause the fuel to vaporize too early, leading to incomplete combustion. Incomplete combustion results in reduced power output and increased fuel consumption.
Therefore, applying carburetor heat during engine operation is generally not recommended, except in certain specific situations such as when flying in icing conditions.