Forget about it unless your contract states a provision for giving you some of your money back if they later lowered the price.

The closest anything like that is ever done is when before a purchase is made the seller makes a price guarantee (for example Best Buy offers a 30-day price-match-plus-10% guarantee). At Best Buy, If you can produce a printed ad from a competitor (not internet) with a lower price within 30 days of your purchase - they will refund the difference plust 10% - IF THEY CAN VERIFY IT). Good luck with that one...

If you don't have such a deal, you don't have squat. Two days after I bought my Jeep Commander, DCC bumped the cashback from $4000 to up to $4500. The only way I could have gotten the $500 is if I took the vehicle back, undid the transaction (and left behind some non-refundable fees) and re-executed the deal. I would have lost money and anyway, I never even considered it. The dates were part of the terms and there's no way around it unless there is fraud.

You have a 1-year old car that has depreciated, the deal was struck, signed and executed, and recent price adjustments have nothing to do with your deal. You could try to sell your car for what you have into it and then go buy a new one but that's the closest you can get to changing things. Do you have the 7/70 power train war.? Does the new deal have it? (I bet it doesn't...)

If you could get an attorney to take the case (you won't) and win in court (not likely) you would set a precedent that fundamentally undermines how business is done in this country. There isn't a judge on the bench that would want to have his name on that decision.