It depends....
Blacknight is quite right, I think. If your site is about BMW and sales and service and parts, and you have a page for each, you won't need keywords.
If however you have 10 sales pages (referring to different people, car models etc) - then you may add in kewords to differentiate between them, or if you want to cater for spelling mistakes (e.g. spelling kewords incorrectly as "Keywords" like I did
)
So many beginners think you have to throw every possible keyword, any related ones and their cousins, you just end up diluting them and they become valueless. Keywords have some value but not an awful lot.