When gas prices go down, sales of electric vehicles go down too, right? And by the same token, you'd think that lower gasoline prices must mean increased sales of gas guzzlers and decreased sales of electric vehicles and hybrids. But that's not the case, new studies show: Electric-vehicle sales, and sales of high-gas-mileage cars, continue to hold steady, while the current increase in sales of light trucks began before gas prices started to fall.