Mercedes-Benz GLA250 vs Mercedes-Benz GLC-Class

What's the difference?

Buuuuuuuur, parp, buuuuuuuuuuuur, parp. Anyone who knows anything about cars immediately recognises the sound of a 45-engined A-class derivative. It's the sound you hear in a tunnel as old mate blasts past with a giant carbon-fibre wing atop his hatchback. It's the sound you hear at 3:00am on a summer morning (if your suburb has no speed bumps, of course).

In short, that sound means big power from a 2.0-litre turbocharged engine, a seven-speed transmission, and a bunch of Germans who clearly had a sense of humour in charge of tuning the exhaust note.

Sure, the GLA compact SUV is probably a slightly unexpected source of all that noise. But then, Merc's Ingolstadt rivals stuffed Audi's stupendous five-cylinder engine into a Q3 to make the hugely improbable RSQ3, so why not do the same with their skirts-lifted A-Class?

To be honest, my expectations for this car were low. So do I owe Mercedes a grovelling apology? Or can I still claim the moral high ground after a week of GLA 45 "ownership"?

Let’s make one thing clear from the very beginning - this new Mercedes-AMG GLC63 S E Performance is technically superior to the model it replaces. Whether it’s actually better or not, is the real question at the heart of the matter.

Why? Because, like the C63 sedan stablemate, AMG has opted to replace the previous model’s 4.0-litre twin-turbo V8 engine with a new 2.0-litre four-cylinder hybrid powertrain. It was a move brought about in part because of increasingly stricter emissions standards in Europe, but also ties-in with the German firm’s success in modern Formula One racing.

While the new hybrid system offers more power, more torque and better fuel economy, as the lukewarm response to the C63 has demonstrated, the hard reality for AMG is that its buyers associate it with V8 and even V12 engines. That emotional pull is hard to replace with logic, even if the new model offers technical superiority.

But how does the new powertrain suit the GLC63 - is it just technically better or is it holistically improved?