Today the two top open-wheel racing series in the US — the Indy Racing League and the Champ Car World Series — agreed to merge, effective with this coming season. Actually, it’s not so much a merger as it is Champ Car shutting down: After 12 years of bitter rivalry that confused fans, promoted apathy and nearly buried the sport, Champ Car agreed to cease operations, giving the surviving IRL the opportunity to rebuild open-wheel’s lost prestige. Champ Car clearly came out the loser in this deal, but considering they went bankrupt a few years back, they’re probably lucky to…