Thick smoke is billowing out of my car's exhaust, can I tell what's wrong from the colour?

I'm concerned there is a serious issue with the car and it's going to cost me a fortune to get it fixed. Can the colour help ...
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What Does It Mean When A Car Is Running Lean?

Ever been told your car is running lean? It means the engine is receiving too much air or not enough fuel during combustion. You see, your car's engine needs a very specific balance of air and fuel to ...