Do the speed limit---good & hard.
The thing I hate most about tailgating is that it's just so stinking stupid. Clearly the driver of the red car is a drooling, cursing moron, but he doesn't see it that way. He may think he's being safe for not going around the other car. But as Wikipedia notes, "Tailgating can occur because of a lack of perceived risk in so doing. Thus, it is done unconsciously or negligently, very often by people who consider themselves safe drivers and generally obey the other rules of the road. Evidence shows that more experienced drivers are more likely to be involved in rear-end collisions, possibly because they overestimate their skill and become complacent about allowing sufficient distance to avoid an accident."
When you see two cars locked in like this cruising down a road, don't you suspect that the car in back is being driven by a restless, irritable, ill-tempered egomaniac, the kind who is placidly convinced of the excellence of his driving skills? In other words, the world's worst father-in-law?
Pound sand, tailgate buddy. You may own a piece of the road, but not all of it, and the way you drive you'll eventually be spread over it like a thick jelly.