Yes, minor lubricity concerns. It's so subjective to say whether the car runs "better". Some seem to think so. It's to early for me to declare, I'm only on my 2nd tank (per pump label).

Lubricity issue:

ASTM spec D975 calls out a minimum of 520 microns (HFRR)

The FIP manufacturing group wants a minimum spec of 460 microns. You can see a gap. So, for those who don't consider the FIP to be a disposable component, you may wish to use an additive that will improve overall lubricity in the fuel system.

FWIW, once the refiners settle into producing S15 (ULSD), we should be buying the best D2 product ever available in N America.