maybe so with older diesel cars but newer diesel cars run much more efficiently and cleaner than unleaded cars. most newer diesels run cat converter systems that store carbon and carbon offsets. then as the catalysts become full the cats burn it off. temps from the burn off get as high as 550-600 celsius. this creates chemical reactions and yada yada etc etc. in the end the outcome is very very minimal harmful emmisions
when i was doing training at holden for this system we tried it and burnt the floor. it turned out your supposed to do it while driving. haha