What's the news?

Not one, but two new BMW M cars are now officially out. Ok, we've known about the M4 Coupé and M3 Saloon for some time now (and yours truly has had the privilege to sit in both already), but it's still an exciting moment for petrolheads everywhere. Most of you will know this, but for the few that are a little confused by the M4 name, there is no longer a 3 Series Coupé in the line-up; it's called the 4 Series Coupé. Hence the M version is the M4. But thankfully the evocative M3 name isn't being put out to pasture, as BMW reveals the four-door M3 Saloon simultaneously. Style and practicality aside, there's nothing to choose between the two. As you'd hope, they're faster yet more efficient than their predecessor, lighter yet stiffer in every direction. And of course there's loads of new technology and more techno-geekery to convey than we have time to write about.

Exterior

You don't really need me to tell you anything here, though I should point out that the bulge of the rear arches and how it interfaces with the shut-line of the back doors in the M3 Saloon is reason enough for me to pin my stripes on it. There's also a more prominent 'gurney' boot spoiler on the four-door car. It gains a carbon fibre roof for the first time too, which saves about 5kg and reduces the car's centre of gravity. On the M4 Coupé it features a recess that is mimicked in the bespoke boot lid, itself sculpted subtly to form a lift-reducing spoiler.

And the aerodynamic trickery doesn't stop there. As in the regular 4 Series Coupé there are Air Curtains in the outer edges of the beefy new front bumpers, plus Air Breathers behind the front wheels to channel the air back out. In the M cars of course it's all suitably more muscular. Do we even need to mention the quad exhaust set-up? Thought not. In terms of wheels, forged 19-inch items are standard in the UK, available in two different finishes.

Interior

The M3 and M4 gain BMW M's new slender three-spoke leather steering wheel and gorgeous leather sports seats front and rear. The whole trim package is bespoke to the M models too and if anyone cares, the rear seat back splits 60:40 in both cars. There are unique instruments of course and lots of driving options to play with. We can't wait.

Mechanicals

As with any new BMW M car, this is the juicy section. And of course the engine takes centre stage. Predictably, BMW has ditched the sensational naturally aspirated V8 engine in favour of a turbocharged straight-six, but it promises to be a bit special. The 3.0-litre unit is fed by two turbochargers, fuel is by direct injection and valve and camshaft control are taken care of by Valvetronic and Double-Vanos respectively. What does all that mean to you and me? Peak power of 431hp, produced from 5,500- to 7,300rpm; 550Nm of torque available all the way from 1,850- to 5,500rpm; and 0-62mph in 4.3 seconds (or 4.1 seconds if you get the optional dual-clutch auto). The top speed is limited to 155mph as standard or 174mph if you pay a little more. Not bad at all. And, if for any bizarre reason someone from the Green Party is reading, these M cars are about 25 per cent more efficient than their predecessors, with emissions as low as 194g/km and fuel economy at 34mpg.

But of course the M3 and M4 have a lot more going for them other than that engine. A lighter six-speed manual gearbox is still standard, thankfully, though purists won't like the fact it comes with automatic throttle blipping on the down-shift (I for one hope it's switchable). The seven-speed dual-clutch M DCT automatic transmission is optional and so-equipped both cars are quicker accelerating and more efficient. A one-piece carbon fibre driveshaft brings drive from the gearbox to the updated Active M Differential, as ever an electronically controlled limited slip unit. Power is, mercifully, to the rear wheels only.

There are pages and pages of details of the M3/M4's chassis make-up that we could replicate here, but in essence it's considerably lighter yet stiffer in most areas. One thing of note is that the rear sub-frame is rigidly connected to the body. BMW also seems to be particularly proud of the electromechanical power steering system, which has a fixed ratio, but alters assistance depending on driver preference and speed. Last, but not least, UK cars will be fitted as standard with the Adaptive M suspension with different levels of damping on tap.

Anything else?

The M DCT gearbox has a few new tricks up its sleeve. When understeer is detected, Stability Clutch Control opens the clutch to help bring the nose back into line. There's launch control as before too, but our favourite, and one that had us double-taking at the press release, is something called the Smokey Burnout function. I kid you not. Apparently it "allows the driver to indulge in a degree of rear wheel spin while the car is moving at low speeds." When I grow up, I want to be a German automotive engineer...

Prices start at £56,175 for a manual M3 saloon or £56,653 for a manual M4 Coupé. The cars will be at the Detroit Auto Show before order books open in June 2014.

Click here for the BMW M3 Saloon gallery