The technical requirements, settings and in particular the observance of photographic rules influence the result of image optimization.
Here are some negative examples and the corresponding negative result:
Starting material smaller than rear panel:
Image 1600x1200, rear panel 4000x3000. Result: Vehicle small to back panel

Quiet background as possible
Restless background leads to error detections e.g. in the windscreen and away retouching of the roof antenna.
If possible, photograph in slightly covered sky (dry weather, less sharp edges and different color nuances on light & shadow side)
Do not photograph in backlight /when sun
Avoid overexposure and underexposures
No shadows of other objects on the vehicle (canopy, photographer, etc.)
Vehicle should be positioned centrally (both horizontal and vertical)
No cropped shots (always leave "air" around the vehicle)
Vehicle should make about 3/4 of the image width
For vehicles recorded too small, these are not zoomed in:
Recording position in approx. 1.5m Height
Both shots from a greater height or frog perspective seem unnatural:
No "creative" shooting angles (from obliquely above, etc.)
Record vehicle as straight as possible (recording position neither rotated nor obliquely)
No vehicles in the background (especially if they are parallel behind the vehicle)
In the rear area, clean separation between the photographed vehicle and the vehicle in the background is possible:
Exempt interior shots without looking outside from optimization (nothing can be optimized here)
When optimized, no change except format change to back panel size / format: