Weather and climate prediction are two entirely different things.
Here's an analogy, it doesn't involve cars:
Take a pot of water and put it on the stove top, and turn the stove on. The analogy of the weather forecaster is that the weather forecaster is trying to predict every eddy, every bubble, every current in the pot of water. It gets extremely difficult to predict all the eddies even 10 seconds from now. The climate scientist on the other hand is just trying to predict the bulk temperature of the water in 2 minutes time. This is much easier to do and can be done with a lot more accuracy. In terms of global warming, the climate scientist is predicting how the rate of change will differ if you now put a lid on the pan, and what difference it will make if you (say) only half cover the pot versus putting the lid on completely.