Hey. first of all...i'm 19 (20 in just 3 months) and i'm going to try to buy my first car myself, by my birthday. in 1-4 months. i only have 1 credit card & it's been open for about 8-9 months. the 2 fico scores i've checked are 713 & 687. I got in the mail today a pre-approval letter for a credit card from american express, "based on your exceptional record of financial responsibility, blah blah blah. I usually throw these away. but I was wondering...i've read before that having more than 1 line of credit open is better for your credit score, but i have also heard that opening a new line of credit or getting a loan, etc...will temporarily make your score drop and then it will go back up again after you start making good on the account. so my question is I guess, would accepting this credit card hurt my score and chances of getting an auto loan within the next couple of months, do nothing at all, or possibly help it? thanks. oh and i'm not in debt or anything. i use my card and pay it in full every month.