Twitter has a new profile format. Unfortunately, most of the manufacturers haven't taken full advantage of it yet. Don't make their mistake.
Ford is one of the only ones that has already changed their's. It's not great - they picked an image that made reading the text a challenge - but at least they have something up. The same is not true for Toyota or many of the other manufacturers.
It's easy. Go to your Twitter profile. Hit "edit profile". Click on the "design" area. Upload a header image. Done!
Make sure that the bottom half of the image is dark and there is no text as your Twitter account description, location, and URL are in small white print there. Your profile image is at the top and centered, followed by your profile name and your @address. For an example, check out TK Carsites' Twitter page (that's a '67 Trans Am, by the way).
Quick and easy stuff, but it can make your profile more attractive for visitors.