A driver can't be a #1 car. The reason is its driven (not factory new or just like factory new). A driver can be any other number, 2-5. A #2 car is original in most every respect but is maintained and driven in first class condition. A #3 car is a very nice car, maintained in much better than average condition but may not be fully original (modified for example)or may have minor defects. A #4 car is restorable to #3 condition or better. A #5 car is a parts donor car. A rust bucket is a rust bucket.