In a 2 week period counts as 1 inquiry for car loan or home loan rates without affecting score.
Inquires make up about 15 percent of your total credit score. Late payments,bankruptcies,repossesions,foreclosure,high debt to available credit ratios is what really kills your scores. The other items have alot smaller impact.
The computer scoring model will ding you after so many credit card,car loan,home loan inquiries spread out because it figures you are applying but NOT getting approved so you must be high risk.
They expect people to shop rates within a REASONABLE amount of time.