Before the Renault Zoe rolls into European showrooms next spring with a promise of affordable electric mobility, the super-mini car cruised to a fuel-economy victory in the English countryside. The Zoe emerged as top mass-production vehicle Saturday in the Royal Automobile Club's (RAC) Future Car Challenge, achieving the equivalent of 163.3 miles per gallon (69.4 kilometers per liter) in the Brighton-to-London road rally. It is fitting that the race ended at Regent Street, one of London's premier shopping thoroughfares, crammed with big-name brands that daily beckon hundreds of thousands of shoppers. French automaker Renault, which has a 13-year-old alliance with Japan's Nissan, aims to...