My cars are diesels, but I don't think that makes a difference. With the engine fully warmed up like being on the highway it should be between 1-1.5 bar. When the rpms get up to about 1500 your pressure should be pegged at 3 bar.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member