I don't see any estimates on the time saved by use of automobiles vs other types of transportation. 
The only places where public transport might be cost effective are densely populated urban areas like NYC. 
Overall, the benefits derived from driving cars far outweigh any costs caused by traffic jams, which people always do their best to avoid.

The bottom line is that cars aren't going away because having a car is far, far more beneficial than using public transport or riding a bicycle.