2015 BMW M3 and M4 images leaked | video

Images of the new BMW M3 and M4 have been revealed via an online BMW blog ahead of their official debut tomorrow. As you'd expect, the photos show a more aggressive treatment for the bodies, with muscular wheelarches housing big alloys, quad exhaust tips, and M badged heat extraction vents behind the front wheels.

Watch the desktop version of the official BMW M3 and M4 video here.

With the new BMW 4-Series already in Australian showrooms  attention will now be focusing on what we can expect in the coming BMW M3 and M4 that are set to arrive next May, 

BMW has alreqady comfirmed the outputs for the cars, announcing them at a technology workshop. The new M3 and M4 will deliver about 320 kilowatts of power and 'far beyond' 500 Newton-metres of torque from the latest 3.0-litre turbo in-line six-cylinder engine.

The M3 gets a considerable hike over the same engine in the 4-Series 435i Carsguide tested in July, which delivers 225kW and 400Nm. But it's less of a jump over the outgoing M3's 4.0-litre V8 with 309kW and 400Nm. The M4's output is said to be 310kW, but we've also heard talk of a bigger 3.3-litre turbocharged six-cylinder that could offer 336kW. The German carmaker says that the engines are also much more efficient, achieving a reduction in fuel consumption and emissions of 'around 25 per cent'.

BMW has reportedly decided on a more modest power hike in favour of a wider torque spread than the V8, also helped by a new cylinder head. In addition, the coming M3 and M4 will be lighter, with weight-saving strategies joining a carryover carbon-fibre roof to keep it tipping the scales in the target range of about 1500kg -- a drop of 100kg on the outgoing M3. More details will be revealed tomorrow, in preparation for the official unveiling at January's Detroit motor show.

Watch the BMW M3 and M4 testing at the Nurburgring.

This reporter is on Twitter: @KarlaPincott