Back in 1999, DC's Vertigo came up with a 4-issue mini-series , "4 Horsemen", depicting how the 4 Horsemen of the Apocalypse would react to a modern world that had evolved beyond the one that they had once set out to destroy in the Dark Ages.
After a moment of deliberation and observation, they adapted by recreating themselves...
Famine, after hearing the story of a woman who'd been on both sides of the Abortion issue discuss the problems of overpopulation, became Fecundity, to increase procreation among those whose stomachs know no want.
War, who'd listened to a corporate shark gloat about how the power and conflict of the world rested in business and industry, not warfare, became Incorporation, to master corporate warfare, cleaner, more ruthless and insidious then conventional warfare.
Plague, who'd examined the memories of a woman who'd spent her whole life suffering from having her entire life constantly under scrutiny by corporations and government, became Information, to conquer a new plague, one which destroys intimacy, destroyes independance, and destroys intiative.
And Death, after recieving an epiphany by looking into the dead mind of a young kid who'd numbed his ability to reason through consumption of mass media throughout his life, became Incoherance, to bring not physical death, but a death of the mind, a kind of living death.
With their new identities and resources, Information, Incorporation, Fecundity and Incoherance became the Four Riders of the Apocalypse resumed their tasks of bringing the world to it's end...
I highly recommend this mini-series, if you can find it. I might use it myself if I start a D20 Modern campaign...
http://www.geocities.com/Colosseum/Track/4619/horsemen.html
) was War, and the X-Man Angel was transformed into Archangel to take on the role of Death. I don't recall the others, though. 
Choppers? Limos?
