We're still impatiently waiting for the all-new BMW M3 and BMW M4 to arrive, but spy shots of work-in-progress prototypes have helped ease the wait. We last saw the BMW M4 Coupe cruising the streets in a new shade of yellow, and now winter testing has begun for the high-performance coupe. This latest BMW M4 Coupe prototype can be seen getting a workout in Sweden, and it looks like the test driver was having a lot of fun making it dance on the snow.

There's still camouflage covering the design details, but the prototype appears to be fitted with slim production headlights and taillights so the official reveal shouldn't be too far away now.

Quad exhaust pipes and wider fenders also distinguish the M4 Coupe from its standard 4 Series sibling. No surprises there, as these are signature design elements on a BMW M model.

However, as we saw in recently leaked photos BMW would rather pretend didn't exist, the BMW Concept 4's controversial grille will carry over to the new 4 Series, M4, and M3. It's a bold move, but it's happening whether you like it or not. We suspect the will be toned down after the BMW Concept 4 was heavily criticized, but this new design direction is bound to cause controversy.

Under the hood, the new BMW M4 will be powered by a S58 3.0-liter inline-six engine - this is the same unit found in the BMW X3 M and X4 M. In the new M3 and M4, this unit is expected to produce 473 horsepower as standard and 503 hp in the range-topping Competition model. BMW will also cater to buyers with different needs, as the new M4 and M3 offered with either rear or all-wheel-drive and a manual transmission.

The new BMW M3 and M4 will reportedly be unveiled this summer before starting production in November. Customer deliveries are expected to begin next spring, so enthusiasts still have a long time to wait before getting behind the wheel.