Hi ,noticed myself same issue today,so looked around also in forums all directing to DPF and EGR,haven't had Lexus before juts got one,high mileage 160k but full Lexus history last done 4k ago,so long story short it drives fine and no warning lights,but in the dark when someone is back with headlights it seems that the smoke is like fog:),got me bit worried today,i will see how it is in daylight,done just 300 mile trip on motorway and did notice anything?If it was a problem with DPF thsi trip should of cleared it a bit,so no idea at the moment,lets see tomorrow....
