collective noun?

Bimbling my way to the dentist[1] this morning, I was taken from behind by a swarm/gaggle/flight/pack of Morgan 3 wheelers, at least two of which sported Mr Prestwich's crackling power plant.
The event brought a smile, and the thought that, if there isn't a collective noun for such a group of JAP engined vehicles, there should be, and it should be 'Rasp'.

[1] Oh the irony.
Live life. Embrace incontinence.
It's your built-in grim reaper radar.