Mercedes-AMG E63 vs BMW 630I

What's the difference?

Feels like lately all the Mercedes-AMG buzz has been at the smaller end of the scale.

Most recently, the screaming GLA 45 S has arrived in Australia, pumping out more kilowatts and newton-metres than any compact SUV has a right to.

But here, we're doubling the cylinder count to eight, arranging them in a vee, and lighting the wick on AMG's powerhouse mid-size sedan, the recently upgraded E 63 S.

While the ferocious twin-turbo V8 and the rest of this beast's powertrain are unchanged, the car has been brought up to speed with some aero-focused styling tweaks, Merc's latest 'Widescreen' digital cockpit, as well as the MBUX multimedia system, and a tricky new multi-function sports steering wheel.

What happens when you struggle to sell an odd-bod, not-quite-a-coupe, sort-of-a-hatchback, almost-an-SUV model? Well, sometimes it gets axed, and replaced with a new model that bears a new name.

That's pretty much it in a nutshell for the BMW 6 Series Gran Turismo, which was formerly the 5 Series GT. It essentially takes the place of the 6 Series Gran Coupe - an alternative to the regular 5 Series sedan that's more attainable than a 7 Series limousine.

Confused? It's not as difficult as all that sounds - you just need to know that this model, the 2018 BMW 6 Series Gran Turismo, is supposed to offer a neat alternative to the go-to family luxury car or SUV.

I spent some time in the entry-level 630i to see if it can deliver on that promise. In fact, I spent more than 24 hours driving the BMW 6 Series GT over the past week, and I don't have a sore back, I haven't been left scratching my head over the intended purpose, I haven't been uncomfortable, and I haven't been left wanting for much.