SO when is a supercar not a supercar? Well according to McLaren, it's the GT, classed as Grand Tourer, but without doubt delivering supercar performance.

Its stablemate, the 720S, has no such nuances and is classed as an out and out supercar.

There's no doubt both deliver supercar prices, with the GT starting at £163,000 and the 720S from £215,000.

Both offer stunning performance on the track or, when permissible, on the open road.

Both look stunning with 720S coupe and 720S Spider cabriolet delivering a brutal 720ps from its four litre V8 engine, while the GT delivers a less muscular 620PS, but both are capable of reaching 200 mph.

Both are light with monoframe bodies surrounded by carbon fibre chassis and aluminium panels, which also allows for good interior space and the lowest kerb weights. At 1,530kg the McLaren GT is more than 130kg lighter than its closest core competitor

There's also practicality in the shape of the GT, with ample room under the full length, glazed, powered tailgate for a set of golf clubs and, because it is mid-engined, space in the front storage area. The 720S is tighter with baggage space behind the seats and 150 litres of space under the front pane.

The low height of the engine and positioning of the exhaust system has allowed the volume, shape and usability of the luggage bay to be optimised.

A golf bag or two pairs of 185cm skis and boots, as well as luggage, can be carried with ease, while a further 150 litres of storage at the front means the GT can accommodate a total of 570 litres.

And unlike some supercars where you need to be a contortionist to get in and out, the signature gull-wing doors offer easy access and egress, although the GT offers the easier access of the two.

They look the part, sleek and elegant with longer overhangs, muscular curves, with large air scoops, showstopping alloy wheels and aerodynamically turned to slice through the air with minimum resistance.

A key feature on the 720S is the absence of radiator intakes on the side of the car, which has been replaced unique ‘double-skin' aerodynamic form of the dihedral doors, which channel air to the high-temperature radiators that cool the mid-mounted engine.

As you would expect with both cars, the cabin is sports focussed, but offers some luxurious leather offset by aluminium switchgear, and high end sound system although not on the same level as a similarly priced Bentley Continental GT.

The GT has a more sophisticated feel, with the 720S more stripped back to unleash the extra power.

On the road, both are remarkably responsive and the harder you push, the better the drive. Both were taken on a simulated Alpine route, followed, a straight mile power run and laps on a two mile oval banked track.

Both are mated to a seven speed auto transmission with the option of using steering wheel paddles.

The immense power and torque of both were evident at all times as was the superb handling on the twisting, sometimes icy mountain track.

With the aid of the new generation of McLaren's Proactive Chassis Control combined with power-assisted, electro-hydraulic steering they deliver a thrilling experience as they cling limpet like to the road on the tightest of hairpins.

They respond with an almost balletic poise as the steering keeps the car where you are pointing it.

In addition the Proactive Chassis Control suspension of the 720S, uses inputs from sensors to ‘read' the road ahead, interpreting what is likely to happen next and reacting predictively in just two milliseconds.

Switch to the straight mile run for blistering acceleration, both the GT and 720 race to 60mph in 2.8 seconds, and 3.2 seconds respectively. Stand on the brakes as they end of the track approaches at 150mph and the car comes to a standstill in just over four seconds.

For those looking for an even more raw, full-fat driving experience, choose from Comfort, Sport, or Track modes for an even more jaw-clenching experience.

Just as impressive is the GT which can hit 60mph in just 3.1 seconds and on to 125mph in just nine seconds, again with instant braking.

And just in case anyone hadn't noticed you, a bespoke exhaust system can deliver a spitting crackling roar under acceleration, or a more discrete sound under more normal circumstances.

Stunning performance, but both are capable of being driven in a more sedate environment with the braking and steering at lower speeds optimised for everyday ease of use as ride height and ground clearances engineered for urban usability

Creature comforts are catered for with the GT offering Standard, Pioneer and Luxe interior specifications with high-quality materials throughout and advanced technologies including ambient lighting, new McLaren Infotainment System II and optional electrochromic panoramic glazed roof.

The 720S comes as Standard,Performance and Luxury trims.

Suffice to say economy and CO2 emissions are nothing to write home about, but when you spend on a car, its not a major issue, is it?

There's no doubt they are superb cars and brilliant to drive. Supercars in the true sense of the word.