OK...thank you. I really think it is just dependent on temps and pressure limits within the bits to contain it...because fuel should be trapped in the rail by the hpfp oulet valve, the fprv and the injectors. Perhaps after a drive the pressure is reaching fprv limits or even an injector may not be holding as much pressure in that brief moment when the pressure is high due to heat. Then after some pressure and fuel is ejected when hot, and it cools down, the pressure is falling way down. For some reason...for the past few drives...it hasn't stumbled as badly upon start-up.Hey!
Had a look today, car sat for about 36 hours (temperature is 10°C) so not sure if it's relevant to you:
230: spec: 49.9bar / actual: 5.8
231: 5 bar / 5.4 bar / load: 5.9%
It starts normally although not as quickly as when hot.
Usually when cooler here, the data looks exactly like yours...5 bar target and 5.5 bar real in the low side...and 6 or 7 bar in the rail.