All below screenshots taken with my presets, RSS showroom and Content Manager.
Here are 19 presets for Content Manager using tha amazing RSS showroom by chargingcar. The RSS showroom brings colors, shadows and reflections back to life.
Download and install my presets from this page you are on (you will find the full instructions inside the zip file) and also download and install the RSS showroom from http://www.racedepartment.com/downloads/rss-showroom-2018.18929/. Then open Content Manager and select one of my presets to create a custom preview or a custom shot of a car.
Download Content Manager from http://www.assettocorsa.net/forum/index.php?threads/content-manager-aka-alternative-launcher.33824/
Open Content Manager, go to content and select a car. Then click Update previews>>Options.
Then click "Switch To CM Showroom" if you have not done yet.
Then go to scene and select a preset or a showroom and take a screenshot by clicking the [+] icon.
Remember to have the latest version of Content Manager, version 0.8.882.17282 or higher, by enabling "Update to non-tested versions" option in Settings>Content manager>General.