Had a similar experience to the original posters incident today.
Germany was a white Golf TDI, Italy was a red 156 GTA.
Germany was ahead, Italy was breezing past Germany traffic making good progress on the open motorway pitch.
Germany sees this, begins to follow. Italy slows down a bit for traffic. Germany overtakes Italy, and in doing so covers the entire overtaking lane in brown smoke.
Italy sees Germany is, in this case, represented by some plonker thinking his diesel has so much torque the earth spins faster when he pushes the pollute button.
Italy waits patently behind. when a gap opens, Italy gears down 3 gears, and lets the V6 loose. Germany is left behind in the horizon before the red line in 5th is reached.
2003 156 GTA Selespeed - Alfa Rosso + black multispokes, Eibach anti rollbars, Quaife ATB diff, 330mm brakes, Bilstein B12, De-cat wrapped manifolds + EQ downpipes + Ragazzon silencer, CDA intake, (carefully) removed interior & Sparco bucket seats + 6 point harness