Sorry pskinner - Cant say as i either of my MX6's have had leaks - The most common is the Boot - Check out previous threads...
If it is leaking simply run your hand over your carpets inc the boot and find out if any are wet - thatll be a good place to start
Then get back to us and im sure we can point out some common issues which may be causeing your steaming up etc.
Regards
G