To list everybody you could follow that has a relation to motor racing is impossible. My advice is look through the people you currently follows's list of people they follow and start there. After a while you will find a good group of people that keep you interested, make you laugh and teach you things.
Twitter is a funny thing. When you try and explain it to people who dont use twitter it seems like a stupid idea and a waste of time.
But once you get past the initial confusion of how it all works you will soon find out that it is a powerful tool for everybody to use and benefit from.
Twitter is many things but I will just talk about it in regard to motor racing and most sports.
In my opinion it has become a viewing companion that greatly enhances the racing being watched wether your at home or at the track.
Most racing commentators in the last few years have come to understand this and now use it live as a tool to improve their broadcast.
If a commentator says something that for them is easy to understand as he or she has been in racing for many years but then sees many tweets asking what they ment by that. The commentator can elaborate on the topic immediately improving the show for you and teaching the commentator at the same time. I believe it has greatly improved the fans enjoyment and if you dont have twitter I think you should give it a go.
Twitter for many sports is taking it places it has never been and is making racing and results available to people who may not have access to a TV to watch the race on that day or may not have any other way of connecting to the sport. I have many followers who live in places where pay TV is a luxury they cant afford and I get the feeling sometimes that there phone is their only real way of being connected to racing.
One terrific thing about twitter is you can contact a person and interact with them in a way that has never been possible before.
I now have real friends all around the world and have been given fantastic opportunity and help all because of twitter. Im a big believer in twitter and social networking and I hope you are or soon will be.