The collector-car world is populated with characters, and with events tailored to appeal to each one’s particular passions. At almost any given time, there is a concours, rally, anniversary gathering, or auction sure to attract those with even the most esoteric tastes. For those who have run the gamut of U.S. and British shows, dabbled in Italy, and kicked tires on Germany’s old-timers, Paris’s Salon Rétromobile features a trove of exotica and a decidedly French take on things automotive. A highlight of this y…