Mimoza, do you mind if I ask what the assessment is for? Also, what software are you using to create these images?
You might find inspiration from studying current car adverts and their composition, as well as paying attention to how car manufacturers choose to portray their cars. i.e. An all-terrain vehicle would be best shown tackling different off-road environments, but a sporty car would have a more modern, slick presentation. Try to show the car you want to advertise in context rather than a generic background. Even if you just use simple graphics to "suggest" it instead of photographic backdrops.