They look very good. Hopefully they work well.
A word of warning about universal fit car seat covers. If they don't fit your seats really well they can crush the underlying foam, put permanent wrinkles in the fabric and badly abrade the seat fabric.
An alternative method is one of the FCS towelling ponchos.
http://www.surfstitch.com/index.cfm/a/catalog.prodShow/vid/43322/catid/665/active/1www.shq.com.au/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=55&category_id=20&option=com_virtuemart&Itemid=50You can pop this thing on then whip your wettie off and drive home dry and comfortable and not putting water and stuff over your seats and floor. No flashing and no draughts up your jacksie.
It looks a bit like Ku Klux Klan resort wear but that sort of adds to the fun. You can add some jump leads and do Abu Ghraib impressions.
If you really need to leave your wettie on and have a kiteboard bag then that makes a good short term waterproof layer in an emergency.