In the past I have counted to ten,and then backwards back to one,over and over.I have also said my ABC's over and over,sang songs I knew all the words to and even carried on conversations with myself out loud.

I think you probably just need to start trying different things until you find something that works for you.I think it will be hard though,to focus on your driving plus focusing on distracting yourself at the same time.So be careful.