PLUS is the extra factor that gives Audi's performance cars a knockout punch.

Lightning fast and dressed to thrill even in ‘standard' form, plus models squeeze out that extra wallop that can turn a tornado into a hurricane.

Among a half dozen newcomers from the German brand are a trio bearing the ‘plus' badge that are poles apart in bodystyle but have one thing in common - a volcanic amount of power.

Leading the way is the 5.2-litre R8 V10 plus supercar, the fastest and most powerful road-going Audi ever built.

It develops 610ps, can scorch to 62mph from standstill in a fleeting 3.2 seconds, has a top speed of 205mph and costs from £134,500.

Heady stuff, and to offer some perspective the numbers are near enough identical to the McLaren 570S and Aston Martin V12 Vantage S though if we're being really picky the Audi's maximum is marginally up on the McLaren and way ahead of rivals like the Porsche 911 Turbo S.

Add a few optional extras like the sports exhaust system at £1,800, a Bang & Olufsen advanced sound system (£1,750) so you can actually hear your tunes, Nappa leather and Alcantara headlining (£4,100 the pair) and a Gloss Carbon engine bay trim and it's easy to hit the £150,000 mark.

The mid-engined R8 comes with an advanced new quattro all-wheel drive set-up and its power is transmitted to the road via a seven-speed Stronic transmission.

And a weight of 50kilograms less than the previous generation car contributes to an official fuel return of 23.0mpg with emissions of 287g/km..

Everything is driver-focused and gives the impression of sitting in a racing car, from the sculpted leather bucket seats to the flat-bottomed steering wheel with its paddle shifts, and 20-inch wheels with ceramic brakes.

Planted, comfortable, agile and unbelievably cool, the R8 plus really is an everyday supercar.

You just press a steering wheel-mounted button that alters the exhaust flaps and the note sounds volcanic; switch the Audi Drive Select to performance mode and that popping crackle on the over-run mimics a sports racer. Just fabulous.

Also receiving the plus treatment is the latest version of the SQ5 TDI that at £51,850 sounds bargain basement compared to the R8.

An SUV with sports car pace it boasts more power, more torque and extra kit compared to its Q5 stablemates.

The first S model from Audi with a diesel engine, it is already something of a flyer, but plus ramps things up a notch.

Its 3.0-litre twin turbo V6 TDI produces 340ps, an increase of 14ps over the regular SQ5 TDI and when the driver floors the throttle, an overboost function kicks in an additional 20ps.

The snarl is sensational and two loudspeakers hooked up to the exhaust system emphasise the full sound, which can be influenced further by choosing from various drive select modes.

Blasting from 0-62 takes 5.1 seconds and top speed is a governed 155mph, nonetheless the SQ5 plus can still return an average 42.8mpg - with gentle handling - thanks to stuff like start-stop and thermal management.

Transmission is both smooth and instant via an eight-speed tiptronic gearbox and the Audi also features quattro all-wheel drive.

Equipment highlights over the SQ5 TDI include privacy glass, a black styling pack, 21-inch alloys, MMI navigation plus, Audi Music Interface, powered tailgate and a rear axle sport differential in the quattro system.

Completing the plus trio is a car that blends lightning with luxury in the shape of the A8 sports saloon, developed jointly by Audi and its specialist high performance division quattro GmbH.

Lifting the power from the 520ps developed by the standard 4.0-litre V8 car to a hefty 605ps, equivalent to almost seven A1 1.0 TFSI models, it is capable of producing up to 750Nm of pulling power on demand.

The big numbers are 0-62 in a fleeting 3.8 seconds with 155mph top end, which can be extended to 189mph with the optional dynamic package. The price is a princely £97,715.