The BMW M5 is the ultimate BMW 5 Series, right? Well, yes, but it might no longer be the best - depending on your viewpoint. That's thanks to the BMW M550i.
On paper, the M550i is an M5 Lite, but given how far the current M5 pushes the boundaries of what's possible in a saloon car, is this diet version actually now the sweet spot of the range for those wanting a fast 5?
A 4.4-litre, twin-turbo, 530hp, 750nm twin-turbo petrol V8, which is nothing short of one of the finest engines on sale, if you happen to be into engines. Consider, too, that Mercedes' equivalent (recently facelifted) E 53 is a six-cylinder, while Audi's is the same. And diesel.
And to put the M550i's V8 into context, the M5 Competition produces 625hp but the same torque, while the ultimate version of the ultimate BMW saloon, the BMW M5 CS, makes 635hp and, er, the same amount of torque.
So here, we have a mere M550i, which makes the same torque as the range-topping CS, even if it offers up some 100hp less when the revs are higher. And the fact that you can expect around 25mpg on a longer run is still fairly impressive given what this engine is capable of.
The M550i's V8 is much the same as you get in the full-fat M5, feeling similarly strong low down in its revs, if not quite a spritely when revved hard. Although it's difficult to notice the difference driving on the road, truth be told.
Indeed, let there be no doubt (if there ever was any) the M550i has ample performance. 0-62mph is dealt with officially and actually in just 3.8 seconds and you don't need to get busy with the accelerator pedal to enjoy its massive mid-range punch when overtaking. BMW's eight-speed automatic gearbox is as sharp and enjoyable as ever.
You can add BMW's M Adaptive Suspension Pro for £3695, which adds active anti-roll bars that prop the car up in tight bends and Integral Active Steering, wich is rear-wheel steering in BMW-speak. Given this is a £70,000 performance saloon, it seems worth the extra, especially given the results.
With it fitted, the M550i has enough real focus about the way it turns into corners and behaves on the throttle through them to be fantastic fun. It feels large on tight country roads, but its steering is precise, it's xDrive all-wheel-drive system complete with clever differential allows confident power delivery and you always know where you are with the brakes too.
In short, you never exit a corner and think: yep, I wish I'd had an M5 with an extra 100hp there.
To the uneducated, it looks much like any other 5 series - given most 5 Series on the roads these days are wearing M Sport trim. As ever, there will be people for whom the M5 badge must be there, as a status symbol more than anything. But those who enjoy moving under the radar will appreciate the M550i's look.
That look comprises 20-inch alloy wheels, of which two styles are available, plus Cerium Grey exterior trim accents including the grille surround, air breather, exhaust tips and door mirror caps.
LED headlights come as standard, but you can add BMW's superb laser LED headlights for £1000 which look great fitted with their electric blue design, but also increase visibility to an incredible 600m and have smart adaptive beam technology.
As with all facelifted 5 Series, the M550i gets BMW's new larger 12.3-inch infotainment iDrive system as standard. It runs the latest software behind the scenes and put simply, is the best infotainment system currently on sale.
That's not just because it now features both Apple CarPlay and Android Auto, and now for free, but because its menu layouts and rotary dial between the front seats continue to ensure it's the easiest system to use while parked and on the move.
Otherwise, the M550i is every bit as good as the standard 5. It'll seat four tall adults in comfort and come with a boot that'll handle a family's luggage without fuss. It's also one of the best-built interiors BMW makes, and the M550i features electric, heated sports seats, black headlining, ambient lighting and an M Sport steering wheel.
The burning question: does the M550i make the M5 obsolete? In practical terms, yes it does. It's easily fast enough, enough fun on the right road, is more comfortable, quieter, doesn't leave you wanting for quality or tech inside and is more than £30,000 cheaper than an M5 Competition. In case you were wondering, it's also better than an Audi S6.
Of course, there will always be enough people who value the impact of an M5 badge and the M5's extra 10%, both on the road and in front of their mates. As such, a debate about whether the M5 and M550i existing in the same range is right isn't worth having. It just is.
But for those people that don't value such things, the M550i is an outstanding bargain, even with a £70,000 price tag.
Model tested: BMW M550i
Price as tested: £71,385
Engine: 4.4-litre twin-turbo V8
0-62mph: 3.8 seconds
Top speed: 155mph (restricted)
Official economy: 25.9mpg