The slow speed serves two purposes. The first, is to emulate the slow, somber, march of the funeral processions of old. The second is to prevent other drivers from separating from the group. You drive close to the other cars in order to prevent people from cutting you off and separating the group.

Can you speed driving a hearse?

Processions must yield the right-of-way to emergency vehicles or if directed by a police officer. The escort vehicle may exceed the speed limit by 10 miles per hour and cross the center line of a road. Other vehicles may not drive between or join a funeral procession.

Is it disrespectful to overtake a hearse?

Hearses usually travel at around 20mph, a speed that has potential to create long queues. While drivers are often wary of appearing disrespectful to overtake a procession, they also don't usually want to feel like they're intruding in the group by driving directly behind it. ... Other guests may also travel behind.