2017 Audi A5 vs BMW 5 Series

What's the difference?

With last year's release of the new A4 on a brand-new platform, we braced ourselves for a stream of new cars based on the elegant sedan. And so it has happened - S4, A4 Avant, A4 Allroad, A5 Sportback, A5 Coupe and now the A5 Cabriolet. All that's left is the RS4 and the metamorphosis is complete.

The A5 Cabriolet is a relaunch of sorts - the drop-top hasn't been with us for a while, leaving us in the clutches of BMW's 4 Series (with its hard-shell convertible roof) and Mercedes' C-Class Cabriolet (soft top). Audi reckons just 10 per cent of A5s will be the Cabriolet, leaving the lion's share to the two-door coupe and five-door hatch - but we're a fickle bunch and might suddenly decide we like them more than that.

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?