Enhancing Classics With Old-Car Style and Modern Mechanicals Once shunned by purists, older collector cars and lookalikes fitted with modern engines, transmissions, brakes, electronic controls and sound systems are gaining new respect. Broadly known as restomods, cars that have been updated under the skin are as easy to drive, and often as safe and reliable, as a new model. And after modernization, these sought-after vehicles are unlikely to be garage queens, gathering dust. The concept has friends in high places. "I'm a firm believer in upgrading old steeds with modern components," Jay Leno, the comedian and enthusiastic collector, told Popular Mechanics. His 1925 Doble steam cars have Corvette front disc brakes; his 1966 Ford Galaxie has many improvements, including rack-and-pinion steering; and his 1955 Buick Roadmaster has a 620-horsepower General Motors big-block crate motor. More and more companies are trying to make these sorts of enhancements into viable businesses. In California, Icon remakes classic Jeeps, Toyota Land Cruisers and Ford Broncos. In England, Eagle turns out new-old Jaguar E-Types. Many garages are willing to build classic Camaros and Mustangs to their owners' specifications, with originality way down on the priority list. Even if you want to go green with battery power or a plug-in hybrid drivetrain fueled by ethanol, as in the latest version of Neil Young's 1959 Lincoln-based Lincvolt, it can be done. If there's one thing these sometimes handcrafted cars have in common, it's that they're very expensive. Singer Vehicle Design, which opened in 2009, builds what the company's founder and creative director, the former Lotus designer Rob Dickinson, calls "our expression of the ultimate air-cooled Porsche 911." Prices vary, but the keys to one of these cars will cost more than $300,000. The cars feature custom-built carbon-fiber bodies that evoke classic 911s from the late-1960s and early '70s, and are built with modifications on a later 964 platform. It takes six months and 3,500 man-hours to build one of the cars, Mr. Dickinson said in an interview. "The business case is a bit tenuous," he said. The car is very expensive, but it's a halo vehicle that shows what the company can do. In his California shop, the British-born Mr. Dickinson has built only eight cars, one of which he showed to the press at Miller Motorcars in Manhattan last month. The car was fairly restrained from the outside, with just fat tires and a modest tail spoiler to suggest its speed (including an estimated 4.5 seconds from zero to 60 miles per hour). The 2,700-pound car's 3.9-liter engine (developed and hand-built by Cosworth from the original 964 motor of 1992 at a cost of $55,000) produces 360 horsepower. Perhaps because it was more attuned to California, the Singer Porsche started somewhat reluctantly and settled into a lumpy, rumbling idle. The driver sits tightly but comfortably ensconced in a supportive Recaro seat in a custom woven leather pattern. A tomato-colored tachometer is straight ahead, with the speedometer and clock to the right. Little details became apparent, like the luggagelike hand pulls to open the doors and the racing-type rear-view mirrors mounted through the vent windows. The long brake and clutch travel was reminiscent of past 911s, and cues to that heritage abounded, but this car brought along many modern refinements. Any doubts about the Porsche's willingness were erased when the throttle was engaged; the car responded instantly to even the most minute input from the driver's foot, producing growls, roars and overtones. The 6-speed gearbox offered short throws and was easy for a novice to use.