Steven Bolton, who sells Mercedes for a living and drives one of his own, says the wear and tear he worries about most these days is on his household budget. Filling the tank of his S-class sedan for the 11-mile, 25-minute commute from his home in Warren, Michigan, to his job at a Mercedes-Benz dealership in Bloomfield Hills used to cost this 38-year-old father of three about $70. Now it’s closer to $120. Plunking down $10 a day on gas, Bolton said he has had to cinch his belt. He only orders lunch once ...