In carrara, you could add a little bit of Reflection to the body paint,. which will make it look better.
I'd also reduce the Highlight and Shininess values on the wheels to make them less plastic shiny.
One thing which may speed thing up for you is ,.
Hiding all the objects for "country lane",. and adding a Plane primitive with a Shadow catcher shader,. where the car and figure will be.
Hiding complex objects or replicators will allow you to work faster and move the camera around more easily,.
Carrara has a special "Shadow catcher" shader, which you can apply to the Plane,. and it'll catch the shadows of the car, in the image, but allow any background to be seen through it,.
this is used when you're compositing an image in a photo editor or video editor, and it makes the process faster and easier.
You would render out an image of the Country lane,.(without the car and figure) then hide or delete all of that scene, to leave the car and figure, which will render faster without all the trees and plants,.. then combine both images.
Hope that makes sense.
If you need any help in the shader room, or anywhere else, ...just let me know,.
this example is using a photo as a backdrop image, and a shadow catcher shader on a plane, to catch the shadows from the pick up truck.
Click thumbnail to see full-size image