Robot car that can carry load of 3kg max

Hey, I'm new to Arduino and I want to build a robot car that will carry a robot arm on top of it. Can someone please tell me which parts I can use to make the robot car and also some tips on the things I should be concerned about?

At what speed?
How far?
With what degree of control?

the speed is around 5ms-1 not very fast but not exactly very slow. Distance- 500m. and if I can get to move forward, backward and sideways.

If your road surface is not hard and flat or rises then you'll run into trouble. You may need larger and wider wheels or build a crawler, with stronger motors and battery.

Shall the arm lift the load, and how?

I'm most probably going to run it on flat surfaces and the arm lifts a light load. I plan on building the robot car and I'm gonna place a 780 grams 5 axis robot arm which I will build from a kit. The arm won't be carrying any heavy objects.

Build the car from a kit too. There are plenty to choose from on line.

thanks, I checked some car kits but some are too small to carry the robot arm and I'm not sure if they'll be able to handle the load of the robot arm.