A cow farting

We visited a vintage car rally at Much Marcle. Lots of stunning cars there from really tatty but well maintained 30s sports cars to half a million pound racing Bugattis. Morgans aplenty in attendance of course. A chap was giving it beans in his Morgan and obviously enjoying himself. As it passed I commented to my sis on the wonderful noise. She said it was just a noise and B said it sounded like a cow farting. I didn't dare ask what they thought of the smell of burnt Castor oil.
Philistines.
I changed the pic. This is more beautiful. I've no idea what make it is.