Petrol and diesel engines
The new Golf Mk8 will get a range of 12V mild-hybrid engines for the entry-level and mid-range variants. The 1.5-litre TSI ACT petrol unit will be carried over from today’s Golf Mk7 but this will be joined by a 1.0-litre three-cylinder petrol motor and an all-new 1.5-litre diesel, which is also likely to be sold as a 12V mild hybrid. Autocar understands that the assistance of the mild-hybrid system’s starter/ generator lessens the load on the engine and reduces the spikes of NOx emissions from the diesel’s exhaust.
One of the more intriguing rumours is that the 1.0-litre petrol engines might not be turbocharged at all, but could instead rely solely on direct assistance from a belt-driven starter/generator motor (SGM). The thinking is that the SGM will provide enough extra power and torque for the base engines, allowing the turbocharger, intercooler and associated piping and control systems to be dropped.
The Golf Mk8’s diesel line-up will include the new 2.0 TDI (codenamed EA288 Evo) engine. VW says the base version of this unit has been significantly re-engineered to reduce exhaust pollution. There is a more efficient and responsive turbocharger and the engine is lighter, loses less heat and has reduced internal friction.
More important, the engine’s particulate filter and catalyst have been resized for improved performance, particularly over time. VW claimed the engine offers an average of 9% more torque and power together with an average 10g/km decrease in CO2 emissions. The firm said the new diesel unit will come in versions ranging from 135bhp to 201bhp and will be seen in Audi models before being installed in the Golf Mk8 next year.
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VW has already released details of the Golf’s 1.5-litre TGI Evo natural gas engine, production of which starts this year. Based on the 1.5-litre TSI engine, the TGI unit uses the same Miller cycle valve timing and a variable geometry turbocharger. It develops 129bhp and 148lb ft from 1400rpm when installed in the Golf Mk7. VW claims that this engine emits about 93g/km of CO2 on the NEDC cycle when it is hooked up to the standard- issue dual-clutch gearbox. Natural gas engines are also lower in NOx and particulate emissions than diesel and cars can be refilled from the gas mains network via small wall-mounted compressors. However, the lack of a natural gas infrastructure in the UK means this variant is unlikely to reach these shores.
The new or upgraded powertrains will be offered in combination with either a six-speed manual or seven-speed dual-clutch automatic gearbox, depending on their configuration. Alongside front-wheel drive, VW also plans to offer optional four-wheel drive (which it calls 4Motion) in selected models, like it has done in the previous four generations of its perennial best seller.
Two kinds of mild hybrid
The big surprise for the Golf Mk8 drivetrains is that VW says it will be investing in both 12V and 48V mild-hybrid systems after the company re-engineered the Golf family MQB electrical architecture (one of the more expensive component systems in a car) to accommodate a 48V system. Until now, 48V mild hybrids have only been used in premium VW Group cars such as the Bentley Bentayga and Audi SQ7.
Frank Welsch, VW’s technical development boss, has already revealed the firm’s new ‘affordable’ 48V system, which uses a belt-integrated starter/ generator/alternator to assist the engine by providing extra power and torque directly to the engine’s crankshaft.