There is first gate (Khwas Khani) which you can pass and take ur car. This stretch is occupied by residential houses. So you can drive past these until you reach the parking place a little before Sohail gate. Most visitors park their vehicles there and explore on foot. However the road ahead of Sohail Gate leads to Garha Sikandar so its regularly commuted area even by public transport. So you can take ur car too.
However you can't take ur car to areas like Haveli Man Singh, Rani Mahal etc.