Rather than taking the customary position a few paces behind the car at the lights in front of him, he jerkily comes to a standstill, rubbernecking all the while as he looks the Lexus up and down. It feels as though me and the car are being sized up for a giant automotive coffin.
But the good news for me and Lexus - but not necesarilly for BMW and Mercedes - is that he simply drives away looking glum.
Lexus have been trying to muscle in on the mean streets of the luxury car market for some years now but now finally seem to be making serious inroads.
This is the first Lexus to benefit from L-finesse, a new design concept which translates into long, sweeping lines and elegant curves.
The third generation GS saloon - launched in March and designed to take on BMW's 5 series and the Mercedes E-Class - shows where Toyota's more luxurious arm is going right. The Japanese motor is far better looking than its rivals, a sleek motorway creeper which turns heads rather than turns people off.
If Signor Mercedes had got his tie stuck in the boot, then at least he would have been fortunate to have his neck attire trapped in a trunk which is far more bootylicious (dare I say Bentley GT-esque) than the more angled model it replaces.
To the front it gets a cute, yet sporting, nose complete with more subtle lighting than is the fashion of late. Inside the GS-L model I tested was a sea of ergonomically- designed luxury - even if the concept of subtle branding hasn't reached the Far East yet.
The driver and passenger seats are akin to very comfortable armchairs, while the rear seating area provides adequate room for three adults but is better suited to just two. I particularly liked the expensive look of the metal effect dials, the keyless entry, push button start and touch-screen interface for everything from satellite navigation to the stereo.
The reversing camera, which beams images to the same screen, is neat. But it's actually easier just to turn your head around.
The GS I tested was powered by a new 3litre V6 petrol engine. A 4.3-litre V8 petrol engine is also available and both are linked to a six speed automatic gear-box.
But the GS does have an achilles' heel. Steering - via a steering which is far too skinny and lets the overall package down - is a little bit neutral. Unlike a BMW, it's not an exciting driver's car. And it isn't quite so refined as a Mercedes on the move.
Instead, it has characteristics which you'll either love or loathe: it's so smooth and quiet that it feels as though even the driver is just along for the ride and is set up for long, luxurious journeys rather than winding roads.
That said, I liked the Lexus GS-L a lot and found it incredibly easy to use for such a large saloon. So it's not overly exciting, but it is practical, comfortable and stylish: A case of neutral handling and head-turning looks.
Which brings us neatly back to the most disappointed Mercedes driver in Manchester.
