Here are some pic I took yesterday,FWIW. Its no fun lying on the driveway with ants crawling on youMy Wife's Subaru Outback tailpipe is sparkly clean, also the beast gets over 34MPG average !
My little Ford TP is sooty and gets 25 MPG ave in the summer.
Both cars have (very) high compression, high specific out put D.I. engines
Maybe I'll take some comparative TP photos when I head out for a grocery run at Noon.
... just BC we like to look at pictures
The Ford looks about three shades lighter than from winter when it was inky black. I used a flash so the carbon buildup is actually a couple shades darker than it appears here.
2021 Subaru Outback 2.5L FB D.I. Tailpipe
Ford Ecosport 2.0L D.I Tailpipe