Let me save you some times. You probably have already google it. Just marketing International, Drive Motorsport International, CMA Silverstone and RSM. These agencies are all very good and will also cater for some of your need. If I was you, after talking to me I would call them and ask for a quote as well...
Well, some of them will not even go near any technical projects. Some of them have not organised a championship, had their own racing team and a strong marketing background.
So where is the difference between them and us? We are a boutique. We are small enough to follow your projects from A to Z, we are big enough to employ the smartest people and newest tool.
Yes, all of them will be glad to help you with sponsors and brand activation. I like to think it this way:
they talk about motorsport - we keep doing it.