Dream scenarios involving cars are often much to do with what we are doing to ourselves on a psychological or emotional level. Being alone in a vehicle indicates independence, while dreaming of the brakes shows our ability to be in control.
The car engine indicates the essential drives with which we have to deal.
A crashing vehicle suggests fear of failure in life, while a car on fire denotes stress of some sort, either physically or emotionally.
To be in a car which is driven carelessly, either by us or someone else, marks a lack of responsibility, while a feeling of being left behind would be shown by your car being overtaken.
To dream of reversing a car registers a feeling that we are slipping backwards into old patterns of behaviour or are having to reverse a decision.