Fairfax Honda - Fairfax, VA - initially would only allow $2500 on a credit card, but allowed us to do $3000 since we were adding about $500 in accessories to the vehicle. We asked to do $5500 but finance manager mentioned 3% fees, etc. So we put the remainder ($2500) on a debit card but he still ran it as credit. Leads me to believe he could have gone higher on the AMEX.. oh well.

This dealer also participated in the American Express auto buying program (highly recommend, btw) which specifically states the dealer will accept AMEX for payment - interestingly the site FAQ states they will accept a minimum of $2000 but to contact the dealer to determine the max amount accepted - I thought they couldn't set a max?