BMW 320d vs BMW 520d

What's the difference?

Over 44 years BMW has produced more than 15 million examples of the 3 Series. That's roughly one every minute and a half... for over four decades.

And the latest, seventh-generation version of what the famous German maker defines as the "heart and soul" of its brand has landed in Australia.

The new '3' is longer and wider. It's also claimed to be slicker aerodynamically, up to 55 kilos lighter, more fuel efficient, and faster.

And it'll need every advantage it can muster to take a chunk out of its arch rival, the all-conquering Mercedes-Benz C-Class.

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?