Lufthansa has quietly lowered fares between Dusseldorf and Newark in a direct response to British Airways dumping fares on the route. The only thing with BA is you’d have to transit LHR, which is not exactly ideal if you just want to get from point A to point B.
For travel between November and March you can book DUS – EWR for only $368. You can buy this ticket then bid for an upgrade to Premium Economy and most likely fly roundtrip in Prem Eco for the price of what Economy usually costs on the route.
Since it’s not a fare sale, I don’t know how long this fare will be in place. Other routings from Germany to New York are also priced attractively in the low $400 range for the same travel period (November – March). This fare is available for most days, but your odds increase with Monday-Thursday departures.