The Oetiker clamps are more reliable. If you look carefully at the design of the Oetiker clamp, you will see that it has no lumps or bulges in the clamping surface. Screw clamps are NOT like this. They have a rather large lump where the screw assy sits. The screw clamps also have serrations or slots for the engagement of the screw. This presents undesired friction which prevents an even distribution of squeeze around the circumference.

The Oetikers are nice and smooth around the entire circumference, and the squeeze is established in the crimping of the loop on the outside. This provides a nice elastic squeeze that is evenly distributed.

The Oetiker clamps have a somewhat wide application in the liquid vending machine industry, and can be bought reasonably cheaply in bags of 100.

Unfortunately, Volvo does not pass this savings on to the customer. The size and clamp style is stamped on the clamp. I seem to recall that the size is about 36mm and sells for a bit more than $1 each in the 100 bags.