BMW 540i vs BMW 630I

What's the difference?

Eco-friendly vehicles are the leather pants of the new-car world; it takes a lot of money to make them look good (but people who own them think they look fantastic regardless). If you don't have a gazillion dollars to drop on a Tesla,  then it's a one-way ticket to Prius town. And really, who wants that? 

But what if it didn't have to be that way? Behold the BMW 530e iPerformance.

Seemingly tired of waiting for the Australian Government to introduce any sort of meaningful subsidy for green cars, BMW has made the choice simple: you can have a petrol-powered 530i for $108,900, or opt for the plug-in hybrid 530e for... $108,900. This is truly revelatory thinking.

There's no specification penalty, either, and the hybrid will power to 100km/h in an identical 6.2 seconds, so you're not even any slower. But you are sipping less fuel, emitting less C02 and basking in the general smugness, and sweet silence, that comes with feeling like you're saving the world.

So what's the catch?

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.