The fourth-generation Volkswagen Jetta was a handsome, unassuming little car. Throw the ‘unassuming’ part out for this particular example—some maniacal shade-tree mechanics have cranked the dial on their Jetta to 11 (or, say, 14) by installing another engine in the car’s ___ end._ Unlike your typical dual-engine car—we know, yawn, right?—this Jetta started life as […]