Does a mosquito flying inside a moving car, experiences a force in the opposite direction of the motion of the car? you told that it will experience a inertial force? But it would be in rest with the outside world and why will we consider it with respect to the car as none of its body part is contact with the car?
Yes, mosquito is not contact directly with the car. But it needsan air for flying. And air in the car is moving with the same speed as car, so it is the reason why we consider mosquito with respect to the car.