We say acceleration is produced in a body when a force acts on it in some direction.When a car moves with acceleration and I'm an observer on ground.What force should I say is acting on the car?
The engine applies torque to tires and they apply forward directed force the car's axel by friction with road.
The road is applying a force of friction on the tires at the line* of contact. This force is carried to the axles and to the chassis due to their rigidity (approximately).
It might be a bit confusing to use active language for the road, but the road's application of force is simply a result of the "action-reaction" principle. The tires want to speed up due to their connection to the engine. But this applies a force to the road. So the road applies an equal but opposite force to the tires.
*If the contact between the tires and the road is a line (ideal), then you have static friction, since there is no relative motion between the road and the tires at the line of contact. However, of course the contact is more a patch of several square inch, and most of the tire is rubbing against the road (i.e., relative motion) so you have mostly kinetic friction.