Over the years I have taken quite a few pictures of automobiles at various car show events. I would like to use the photos to create several calendars and market these calendars. Am I violating any law by using these pictures in the calendar? Do I need to get any type of permission from the owners?
You can use the photos, but proceed with caution. Because you took the photographs, you own the copyright to them and can reproduce them without permission. However, make sure your photographs don't contain an image or work that is protectible under copyright law. For example, if there is a mural in the background or if there is original artwork or imagery on one of the cars, you would need the artist's permission.
In general, typical restoration of an automobile is not protected under copyright law unless it is involves ornamental customization, such as that performed by the legendary Big Daddy Roth. There is no fine line that separates protectible from unprotectible car customization. However, the general rule is that customization that is functional cannot be protected. Also, although it is permissible to use the names and trademarks of the cars for informational purposes, you should not use them in the advertising, promotion, or cover of the calendar.
As for the owners of the cars, the rules regarding use of their names in your calendar are the same as for trademarks. Informational uses are permitted, but not commercial or promotional uses.