Volkswagen has already shoehorned the fuel-sipping diesel-electric powertrain from its XL1 technology demonstrator into the Up! city car, but word on the street is that VW may apply the XL1's tech to the volume-sellling Golf before the end of the decade.
The XL1's two-cylinder diesel engine and electric motor combo is capable of delivering a hyper-frugal average fuel consumption of just 0.9 l/100km, though much credit must also be given to its low-slung, ultra-slippery and ultra-light carbon fibre shell.
Will the next-generation Golf achieve such an incredibly fuel consumption figure? Probably not, but the experience gleaned from the XL1 program will apparently be used to help cut down its thirst.
However that doesn't mean the Golf will receive a two-pot diesel and electric assistance motor. Instead, the aerodynamic knowledge that was applied to the XL1 (pictured) will instead be used to significantly reduce drag and thus improve fuel consumption.
Lightweight engineering will also cut down the eight-gen Golf's kerb weight, though in the interests of keeping production costs low, VW isn't expected to employ aluminium or carbon fibre in the new Golf's construction.
Powertrains will remain conventional, with turbo petrols and diesels making up the range.
Clever tricks like electric turbochargers and a coasting function may be added to help maximise power while minimising fuel burn, and will work with the existing electric power steering, smart alternators and engine start-stop features.
A variable compression ratio engine is also under development and may see service in the new Golf, though little is currently known about the VW Group's plan for the technology.
Another potential fuel-saver is an energy-storing flywheel mounted to the rear axle.
By storing kinetic energy during deceleration and releasing it when accelerating, it reduces the fuel burn of the combustion engine while simultaneously being lighter, less complex and cheaper to manufacture than a hybrid assistance system.
Though Volkswagen has not announced any plans to introduce a flywheel system on any of its cars, Volvo is currently developing a flywheel system of its own that can add around 59kW of power for up to 10 seconds.