Classic car "rallies" here are generally static rather than mobile so photos from the ones I get to are almost always of the cars and other vehicles at rest or moving very slowly (the usual one I get to has a 5 MPH [8 km/h] limit on the site) so no panning required.
Hi, we have several kinds of events here.
Meetings means people and their cars get together in one place. If there is enough room, and people do not get in your way,
you get pics of static cars.
Outings means before people drive along scenic routes they get together, so static cars and cars in slow motion.
Rallies, like the Heidelberg Historic: vintage and classic cars meet somewhere, get a tec inspection, and a roadbook is handed out, and the cars travel within speed limits
(60mph on country roads here). Again, you get pics of cars at rest, with no people in your way during the driver's briefing, and cars in motion (if you get route information).
Galas, like the Schwetzingen Classic Gala: Here you get cars at rest. The organizers grant me admission (press badge) before the general public, so I have no spectators in my way
(only owners at times).
Over the years, I know which events to visit in my territory, so I am happy with the results, and usually there is a nice restaurant in the area "after my hard work" ...