West Coast is probably due to CARB Diesel formulations.Very interesting and lots of information, thanks for posting this Lightflyer1.
US is on pages 136-147, and it's interesting the difference in the observed cetane numbers
East Coast - max 48 - mean 44 - min 39
Mid West - max 54 - mean 45 - min 40
West Coast - max 54 - mean 50 - min 41
How is your CR Passat liking a diet of Murphy USA fuel with a minimum of 5% BD?That is why I use stations with a bio component (at the pump) almost exclusively (0 to 20%). All the ones with 5 to 11% bio were under 200 HFRR scores. Not cold enough here for a winter additive and I have never found any water in the fuel since I started in 2005.
Infineum 2018 Winter Diesel Fuel Survey
From the graphs for the US it seems Cetane levels are on the rise and lubricity levels (HFFR scores lower) seems to be on the rise. CFPP seems the same or somewhat improved.
Even then you still wouldn't know which few stations they tested. It is just a very, very general survey. Probably less than a thousandth of one percent of available stations tested. But I do wish they would provide the names and locations of the stations they test, and if they test the same ones every year. It does seem to show at least some progress is being made over time.