Like gasoline...both fuels ( hyrogen and gasoline ) are combustible and dangerous. If the manufacturers can contain these fuels in a safe environment then why not consider hydrogen coming out of water. It's cheap and very much available everywhere

Here's a site regarding water fueled car:

http://www.wasserauto.de/html/daniel_dingel.html
http://www.wasserauto.de/html/inquirer_article.html

For deuterium, its a natural fuel and much cheaper than oil.