You should be paying .00124. Discount is awful too. Dealer would make a fortune off that deal. For M-B, best deals are usually about 15% discount from MSRP with base MF (buy rate) and base acquisition fee ($795). Dealer is trying to work you over.
@kushwiz, C300 is a volume car. This should be an easy one. Email dealers asking for an adjusted cap cost on that car of $37,500 ((.85*MSRP) + 795 acq fee)) and base mf of 0.00044 (after autopay and max 10 MSDs) and base acq fee ($795). This formula should yield a payment of around $375 (depending on your particular sales tax rate), which is about right for a $43k C300. I doubt you will have an issue – dealers need to sell a bunch of those C300s to meet volume targets. You may have to wait until the end of the month, but lay the foundation now. Also, see if you qualify for any discounts (fleet, etc.) Fleet in particular is worth $2,000 and would reduce your payment a further $50 or so. Also, consider the pre-paid maintenance as it is residualized and will only increase your payments a few bucks.
Do not pay a marked up MF, use base MF and bring it down as much as you can with security deposits and autopay. With 0.00174, you will be paying more than 130$/month as interest on your lease. My recent C300 experience is shared here: