What if you have a media area that’s shows messages. So for example when you put out a new car you announce it via press release and on your car companies twitter. This will see a temporary boost in sales because its new and you paid for a press release. Your twitter also gains followers as you get more market share and incline/decline due to “events”. This would then help your sales amounts. “cliff’s car company announces release of beasty car 5000”.
Also being able to show off cars at a car show once every so many days. If you have ever played game dev tycoon you have a marketing event that improves “fans”. This would then improve your social media followers used above.