Never saw it before.
From what I gather, It's like Chevron with Techron... Additives.
I wasn't gonna buy any until I knew for sure what it was though.
This is distributed by Exxon/Mobil.
https://www.exxon.com/en/synergy-diesel-efficient-passengerComing to a station near you
Synergy Diesel Efficient fuel is rolling out across the US throughout 2018 and 2019. The next time you fill up your diesel car or truck, make sure to try the diesel fuel that helps improve mileage and deliver more power. Just stop into your local Exxon™ or Mobil™ station, and look for the next-generation Synergy Diesel Efficient-branded pumps.
Wish I'd filled up at that price now...