I picked up this site from The Daily Telegraph and according to the article, many vehicles they examined have seat defects which make you prone to whiplash injuries.
Models rated poorly include the C-Class, BMW 3- and 5-series, Hondas and VWs, while some Nissans, Fords and Renaults passed with flying colours. Have a look:
http://www.thatcham-sites.org/ncwr2/jsp/index.htmlThe site
http://www.thatcham.org also contains other features on vehicle security.