What's this then?

It's the new McLaren 540C Coupé, joining the 570S in the newly minted Sports Series range and making its world debut at the Shanghai Motor Show in China. It's the new entry-level McLaren basically, set to take on upper models in the Porsche 911 and Audi R8 ranges.

I notice you didn't say 'cheapest'...

No, there's nothing cheap about the 540C. Leaving its £126,000 asking price aside for the minute, it shares all its important bits with the 570S, which, as you may know, shares rather a lot with its big brothers, the McLaren 650S and P1.

Such as?

The carbon fibre chassis for a start. Although it's the second generation of McLaren's 'MonoCell' structure (designed for easier access to the car), we've already seen it in the 570S. Bolted to that, in the middle of the car, is the venerable twin-turbocharged 3.8-litre V8 engine and its slick seven-speed dual-clutch transmission. Drive is to the rear wheels too.

Presumably it's a little slower, though, right?

On paper anyway. As the name suggests, the McLaren 540C's engine produces up to 540hp. Neatly, there's also 540Nm of torque on tap - from 3,500- to 6,500rpm as well. That's down 30hp and 60Nm on the 570S, but is 'ample' by any other measure. It enables the 540C hit 62mph from rest in just 3.5 seconds (the 570S does it in 3.2 seconds) on the way to a 200mph top speed.

What about cornering?

We don't expect there to be much in it. The 540C shares the 570S's new suspension system, which has double wishbones and anti-roll bars, plus adaptive damping, though junior apparently has had a damper retune to make it more comfortable. Owners can choose Normal, Sport and Track settings.

Will anyone know if I go for the cheaper car?

Only us anoraks. The wheels are unique to the 540C - measuring 19 inches up front and 20 inches at the back - and they can be finished in silver or 'stealth', which is a no-brainer, right? Along with that there are a few subtle body work changes to alter the aerodynamic balance.

And inside?

Most buyers are likely to personalise their cars to some degree, rendering the standard specification irrelevant. But for the record, the McLaren 540C comes with plenty of leather trim plus an upright seven-inch touchscreen system that manages everything from the climate control to the standard satnav and DAB radio.

Where's the catch?

We're still asking ourselves that question.

Shane O' Donoghue - 20 Apr 2015