Marvin takes a new car for a test drive. Marvin straps himself into the seatbelt and the dealer says something like, "Oh, you don't need to put that on." (This is 1960s remember.) Marvin then proceeds to destroy the car under a bridge to get info out of the dealer.
The rest of the film is very slow and when this part came along I had a totally new respect for it.
The guy possesses no conscience and will annihilate anything in his way, although not with the mindless bombast of today's Hollywood. I like the comparison that others have drawn to the Stranger in High Plains Drifter (Clint Eastwood, 1973).
Slow????????????????????????????????? Did we see the same movie--is there another "Point Blank"? That was a terrible thing to do to an Imperial convertible; I would far prefer that he destroyed a Mercedes!
I did find the film a little slow. It is just my single opinion and you obviously found it faster-paced than I. It depends on what other films we like and how we are conditoned towards what we experience.
As for the car being a Mercedes, check out the film Driver. The main character does the same thing to a Merc in a car park - surgically taking it to bits by crashing different sections of it to impress his new boss he has to drive around.
Of course this hardly dull film is going to come across as comparatively slow, when we have all been conditioned with today's crop of post MTV-era adrenaline producing action (and many times even non-action) movies, where every shot is contrived to keep one awake, even in shots that are stationary in nature but the camera is made to dance the flamenco. Audiences ought to get past their conditioning, dig up their patience, and judge especially older films on their own merit. .
Some of my most favorite films could be considered quite slow and boring. However, I found that Point Blank simply didn't engage me like some other slow films did. What I took away from it at the end was this memorable sequence with the car. Each to their own...