Dyed-in-the-wool purists might call it sacrilegious, others will see it as progress; fact is that the M division's latest machine keeps with the downsizing times by dropping the previous normally aspirated V8 in favour of a turbocharged six-cylinder.
It also marks an identity change as the Coupe becomes an M4 as it moves into the new 4 Series family, while the M3 badge remains on the boot lid of the Sedan.
The two cars share the same heart.
MORE MUSCLE, LESS WEIGHT
Not only is this new six-cylinder twin-turbo mill marginally (8kW) more powerful than the previous V8, but it's also relatively high-revving, with its maximum output of 317kW produced between 5500 and 7300rpm and the redline at 7600rpm.
Yet that doesn't tell the whole story.
Twisting force is up almost 40 percent, from 400Nm to 550Nm and BMW's lightweight design concept for the whole car means the new cars are about 80kg lighter than the previous M3.
What this means in the real world, and the drag strip more specifically, is that both the new M3 and M4 will screech from standstill to 100km/h in just 4.1 seconds when fitted with the optional seven-speed M double clutch gearbox. Purists, of course, will revel in the standard six-speed manual 'box, which has a throttle-blipping function on the downshift.
Top speed is electronically limited to the usual 250km/h, although buyers paying extra for the M Driver's Package will be able to wind it to 280km/h.
The advanced, downsized engine, coupled with the weight reductions, also result in fuel consumption and emissions reductions amounting to around 25 percent, with BMW claiming combined fuel consumption figures of between 8.3 and 8.8 litres per 100km. Good luck achieving that in the real world.
LIGHTWEIGHT SUSPENSION
To get the new 'M'onsters through the twisty bits with the stunning agility you'd expect from an M3, BMW redesigned both axles with "painstaking attention to detail", with the double-joint spring strut front and five-link rear axle both making extensive use of lightweight materials.
What's more, the car's control unit precisely analyses every driving situation and uses the Active M Differential and DSC stability control to maximise stability by apportioning power to the right wheel at the right time. The diff's degree of lock, between 0 and 100 percent, can be adjusted within a fraction of a second.
However, the ultimate proof was in the thousands of testing laps around the Nürburgring Nordschleife, performed during the development phase by DTM drivers Bruno Spengler and Timo Glock, among others.
Spengler had this to say: "The suspension has a very sporty set-up, the feedback from the front axle is extremely direct, the grip at the rear axle is phenomenal and the engine performance is awesome. This is the ideal basis for our DTM car."
Given that the M Division's new monsters will practically live for track days, both cars are fitted with a track-specification cooling system to help them keep their cool under the harshest conditions.
ADAPTS TO YOU
Those seeking a better balance between comfort and dynamics can order the Adaptive M suspension, which allows the driver to choose between Comfort, Sport and Sport+ damping modes.
Those same settings can be dialled in for the newly developed electromechanical steering system that, unlike the aforementioned suspension, comes standard on the M3 and M4.
Aerodynamic performance was a key factor in the design of the new M3 and M4, and both cheat the air with components like a powerfully formed front apron, smooth underbody, twin-stalk-style mirrors and clearly defined rear spoilers.
Both cars sit on 18-inch M light-alloy wheels with mixed-size tyres, while 19-inch alloys, in Ferric Grey or Black, will be available as an option.
ADVANCED TOYS
That options list is vast and in addition to the items we've mentioned, M3 and M4 can be ordered with a wide range of driver assistance systems and mobility services, including new-generation Professional Navigation with 3D map display, Driving Assistant Plus (which warns of impending collisions with pedestrians), Active Cruise Control with Stop & Go function and anti-dazzle LED High Beam Assistant.
How much is the M3 and M4 going to cost though?
That we'll find out closer to the South African launch, set for the second half of 2014. Where did we hide that piggybank again?