Hello I am looking for guide service english, and cheap car rental for full day in Nanjing.

Do you travel alone? If so, you may have booked hotel in NJ. I suggest u turn to your hotel to find a full day tour guide and rented car for you.
If you are a group, you can join the one-day trip in NJ. In this case, I suggest you use the service of TravelChinaGuide. They will arrange the itinerary, guide and car service for you. Here is their email: travelchinaguide.com|tours in case you would use.

No, i wont be staying in any hotel, coming via shanghai in the morning and leaving to kaifeng in the evening from NJ.
So let me know any local car rental agency where i can go to specific sights of my own.