After six model generations and 29 million cars produced since 1974, Volkswagen introduced the seventh-generation Golf compact hatchback at the 2012 Paris Motor Show. The goal for this generation, reported Ulrich Hackenberg, Volkswagen board member responsible for product development, was weight reduction.
The new Golf has a mass reduced by as much as 100 kg (220 lb) compared to the outgoing model, he said. Much of this reduction, 37 kg (82 lb), was trimmed from the vehicle’s structure. A cost-sensitive model like the Golf cannot justify the use of expensive high-strength steel to reduce mass, so instead the company developed a warm-forming process for its conventional steel unibody.
This let engineers trim thickness from the steel while retaining the necessary strength, he said. High-strength steel, in addition to being expensive, poses the problem of spring-back from the stamping process into an unpredictable shape. The Golf’s steel is unique to this purpose, but it falls in the category of conventional steel, said Hackenberg.
This warm-forming process heats the steel to 950°C (1740°F) to stamp it. Then the stamping die must be cooled back to ambient temperature before stamping the next panel, a process that limits production speed to one stamping per minute, he said.
This process permits variable thickness of the sheet metal throughout the stamping, which means a single stamping can substitute for multiple parts on the previous model. That saves enough to recoup the added expense of warm forming, Hackenberg said. “In total we are less expensive.”
While warm forming is saving significant mass, there is more to be gained as VW becomes more experienced with the process, Hackenberg added. “We can find another five or six kilograms.”
As much as 40 kg (88 lb) is saved through lighter engines, in models that now use aluminum blocks in place of cast iron, with a minimum reduction of 20 kg (44 lb). The aluminum block engines won’t be installed in U.S. models from the beginning, but they will arrive during this model generation, he said.
The new car is instantly recognizable as a Golf, but the company’s MQB transverse engine platform let designers push the front wheels 43 mm (1.7 in) forward. This trims the front overhang and visually lengthens the hood, which is a typical characteristic of more expensive models. This lends the Golf some prestige at no additional cost.
In addition to the regular Golf models, VW also showed the new GTI sport model and the fuel-sipping BlueMotion diesel. The gasoline engines for the U.S. market will initially carry over from the current car, but the European-spec cars will be turbocharged, direct-injected models.
They will have either 1.2-L 63-kW (84-hp) or 1.4-L 103-kW (138-hp) I4 engines. The 103-kW engine features cylinder deactivation to let it run on only two cylinders under light load, acting between 1400 and 4000 rpm and a torque level up to 85 N·m (63 lb·ft). Fuel consumption is 4.9 L/100 km for the base engine and 4.8 L/100 km for the upgraded engine.
Available diesel engines are 77-kW (103-hp) and 110-kW (148-hp) I4s of unspecified displacement that deliver fuel economy of 3.8 L/100 km and 4.1 L/100 km, respectively.
The GTI features a turbocharged 2.0-L I4 of 162 kW (217 hp), with an optional power pack to boost output to 169 kW (227 hp). It is equipped with automatic start/stop in either case and achieves consumption of 6.0 L/100 km.
The BlueMotion car sips just 3.2 L/100 km, while its 1.6-L I4 diesel produces 81 kW (109 hp).
In European markets, the Golf will feature a variety of crash-avoidance technologies such as a multi-collision braking system that automatically holds the brakes after an impact in anticipation of a possible follow-up collision, as standard equipment. Those are unlikely to be included on the base car in the price-sensitive U.S. market.
The Golf reaches European showrooms in fall 2012, while the BlueMotion version will arrive in summer 2013.