I've always found the "Two Trains" problem slow and boring, so I decided to spice it up a bit. You're driving a police intercepter chasing a pair of truly bad men. When you catch them, you don't have to worry about Miranda rights; you get to shoot them ... with a bazooka!
Watch out! The robbers' car may have negative speed. This would indicate that they are now headed TOWARD you with the intent of ramming your car head-on. In that case, you might wish to switch from the intercepter to an army tank.