Aston Martin is developing its own straight-six powerplant - possibly with hybrid tech - to eventually replace the Mercedes-AMG-sourced V8, according to a source close to the firm.

It is believed that work is already underway on the powertrain, which will be crucial to helping Aston meet tougher future emissions legislation. The most likely first recipient of the powertrain would be the soon to be launched DBX crossover.

Aston Martin signed a technical partnership deal with Mercedes-AMG back in 2013. The deal allowed the British brand access to the AMG's 4.0-litre twin-turbocharged V8, which today can be found in the DB11 and Vantage coupes.

However, Autocar UK understands that the engine-sharing part of the deal was only ever meant to be temporary while Aston engineers work on a straight-six, which could be derived from Aston's current 5.2-litre V12.

Technical details of the engine are still firmly under wraps, but it looks likely to utilise hybrid technology developed through the brand's Rapide E programme. While a full plug-in hybrid isn't expected - Aston reckons the charging experience "isn't premium enough" for its customers yet - it should still combine the performance expected of an Aston with efficiency unheard of for the brand.

Aston will make use of the Mercedes-AMG deal for another few years yet, launching its hotly-anticipated DBX next year. That car will feature turbocharged V8 and V12 power initially, with a long talked about hybrid variant due early in the next decade. 

Also read: Aston Martin DBX shown in near-production form before 2019 launch