The Volkswagen XL1 is a high-technology, high-cost plug-in hybrid that, while intriguing, will do very little do directly change the automotive landscape.

Like many such projects though, lessons learned from its development and status as a rolling economy experiment could help production vehicles--the next-generation Volkswagen Golf, for one.

The paint is barely dry on the current generation Golf but according to Autocar, work is already underway on the next-gen car.

New car development is a time-consuming process, but strict European fuel economy and CO2 targets mean the pressure really is on to make regular passenger cars a great deal more efficient.

Current proposals mean a fleet-wide average of 95 grams per kilometer of CO2 could be in place by 2020--the equivalent of 57 mpg for gasoline vehicles and over 65 mpg for diesels.

The eighth-generation Golf is expected to appear around 2019. Given its position in Volkswagen's range, it could mean reducing the average CO2 output of the model itself to less than 90 g/km, to ensure larger cars or high performance models, with higher CO2 ratings, are somewhat offset.

2014 Volkswagen XL1 (Euro spec) - First Drive, Wolfsburg, June 2013

2014 Volkswagen XL1 (Euro spec) - First Drive, Wolfsburg, June 2013

Numerous eco-tweaks

While the Golf will never become as extreme as a car like the XL1, Volkswagen's eco-supercar could lend inspiration.

Autocar notes that mere engine changes may not be enough to reduce fuel consumption enough to hit the strict 2020 standards.

With aerodynamic tweaks and other eco-concessions though--such as shedding weight, decoupling drive for coasting at speed, and even electric turbochargers--a car like the Golf could become much more efficient.

The XL1 itself is already expected to lend its twin-cylinder diesel hybrid drivetrain to the Volkswagen Up minicar, a vehicle previewed in the TwinUp concept.

More difficult will be replicating the aerodynamics of a car like the XL1, given the constraints of a five-person cabin, adequate luggage space and larger, more refined engines.

The car will ride on the same MQB platform as the current model, and while Volkswagen is sure to reduce weight--entry-level cars may hit 2,400 lbs--cost constraints mean widespread use of composites and even aluminum is likely to be low.

It's those costs that could make the project a difficult one. In a limited-run vehicle like the XL1, cost isn't an issue--but on a car that sells in the hundreds of thousands, cost must remain low to continue enticing buyers into the showrooms.

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