It's true you can do the car dealership thing, but is your time really worth less than the $10 it would cost to run it on your own?
You can estimate your FICO score here:
http://www.bankrate.com/calculators/...alculator.aspx I used this before buying my last car and the score that the rep came back with was in this range.
I dunno about a 100-150 point discrepancy. That seems exaggerated and has not been my experience using online reports and getting data from dealerships, when I bought my house, etc. However, I'm sure the auto industry gets a different type of score that has parameters that a "regular" credit score doesn't take into account.