The BMW testing group was spotted in the Alps and allows us to take a look at the M3's rear end with its quad exhaust setup. Under the hood it will probably get a six-cylinder, twin-turbo 3.0-liter engine developing around 450 bhp (335 kW) and 405 lb-ft (550 Nm) of torque. It should complete the 0-62 mph (0-100 km/h) run in 4.2 seconds before hitting an electronically-capped top speed of 155 mph (250 km/h).
The 4-Series Convertible was riding with the top down and had the optional M Sport Package. Engine lineup will probably be taken from the coupe so expect a 4-cylinder, 2.0-liter mill with 240 bhp (179 kW) and 255 lb-ft (345 Nm), together with a stronger six-cylinder, 3.0-liter rated at 300 bhp (224 kW) and 300 lb-ft (406 Nm).
The 4-Series Convertible will make its public debut in September at the Frankfurt Motor Show and go on sale before the end of the year, while the new M3 will come out in early 2014.