There was a time in the mid-1990s when German car brand Audi pitched itself as the BMW for the 'thinking driver'.It was the more sensible and thoughtful 'good boy', in contrast to the 'bad boy' image of its rival.This contrast was epitomised in a humorous black-and-white advert, which saw a sharp-suited 'loadsamoney' City trader bragging about his selfish, uber-competitive lifestyle while test-driving a new Audi.As the insufferable character returned the car, the cultured Audi sales assistant asked what he thought.'Not really my style,' he replied, tossing back the keys before hailing a taxi - clearly more suited to a BMW. The message: Audi was for civilised people.Somewhere along the way, either Audi or the world changed - likely both.Today, Audi has embraced its inner 'bad boy'. The latest example is the racing-inspired RS 5 - the firm's first plug-in hybrid high-performance RS model - which I've been testing on the Côte d'Azur.Available as a rakish RS 5 Saloon or sporty RS 5 Avant estate, Audi calls it 'a new interpretation of RS in a new era'. Audi might have a luxurious and sensible reputation, but its RS cars are a completely different breed. Ray Massey has been out to the South of France to drive the latest German bad boyIt combines a 2.9-litre V6 twin-turbo petrol engine with a 130kW electric motor and eight-speed Tiptronic gearbox to produce 639hp - enough to propel it from 0 to 62mph in 3.6 seconds, with a top speed of 155mph or 177mph in higher-spec versions.It's big and immensely powerful, yet feels planted even on tight bends.There are three trim levels: the RS 5 Saloon starts from £89,400, rising to £95,486 for Carbon Black and £107,485 for Performance Vorsprung. The Avant estate begins at £91,300, rising to £109,385.UK deliveries begin in July. Not for everyone - but bad boys and girls will love it.Both versions share the same length (4,894mm), though the Avant has a larger boot.The saloon offers claimed fuel economy of up to 74.3mpg with CO₂ emissions from 87g/km, with the Avant only slightly behind. Power is generated by a 2.9-litre, 510 horsepower V6 twin-turbo petrol engine, with a 130kW electric motor and an eight-speed automatic Tiptronic transmission with manual override to produce a total 639 horsepower The inclusion of Audi's famed quattro all-wheel drive means it can hit 62mph in just 3.6 sec up to a top speed of either 155mph or 177mph on high-spec carsTrim levelsEntry-level models ride on 20-inch alloy wheels and feature black styling details across the exterior, including spoiler, trim and badging. Matrix LED headlights and a full-width rear light strip come as standard.Inside, there's an 11.9-inch digital cockpit, 14.5-inch infotainment screen, head-up display and a 10.9-inch passenger screen. The system also shows real-time hybrid performance data.Carbon Black versions upgrade to 21-inch alloys and add high-gloss carbon finishes across exterior elements.Top-spec Performance Vorsprung models gain more aggressive RS bumpers, enlarged air intakes, a distinctive rear diffuser and a sportier exhaust note. They also feature upgraded Digital OLED rear lights with selectable signatures and warning displays for other road users.The interior is enhanced with upgraded materials including Nappa leather and Dinamica microfibre, along with heated RS sport seats with massage and ventilation. The flat-top-and-bottom steering wheel includes integrated drive mode controls. ng. UK deliveries begin from July. Not for everyone - but bad boys and girls will love it, says Ray Lap and sector times can also be logged by the system and compared across multiple runs. Ray says he spent most of his time driving on the road, negating the need to log telemetry dataKeeping on trackPerformance is boosted by RS sport suspension and a new quattro drivetrain with rear torque vectoring, which can distribute power between wheels in milliseconds, helping maximise grip and stability.A 'boost' function delivers maximum acceleration in 10-second bursts for overtaking.For track use, the system can record detailed driving data including lap and sector times, acceleration, braking, G-forces and tyre pressures. It can even create custom track profiles based on recorded laps. There are three trim levels to choose from. The entry RS 5 Saloon costs from £89,400 A special Audi 'driving experience' function enables in-depth analysis of the driver's actions, particularly during circuit use Will it fit in my garage? New Audi RS 5 saloon On sale: Now First UK deliveries: JulyPrice: from £89,400 on the road (Avant from £91,300)Length: 4896mmWidth (including mirrors): 2099mmHeight: 1428mmWheelbase: 2903mmWeight: 2,355kgPlug-in Hybrid Power: 2.9 litre 510horse-power V6 twin-turbo petrol engine linked to a 130kW electric motorTotal power output: 639 horsepowerTransmission: eight-speed automatic Tiptronic transmission with manual overrideDrive: quattro all-wheel driveAcceleration (0-62mph): 3.6 secondsTop speed: 155mph (standard) / 177mph (Performance Vorsprung trim)Fuel economy: up to 74.3mpgCO2 emissions: up to 87g/kmBoot capacity (stantard): Rear seats up: Saloon 331 litres / Avant estate 361 litresCapacity with seats down: Saloon 1,170 litres / Avant estate 1,302 litres Speed and performanceStandard RS 5 and Carbon Black models are limited to 155mph, rising to 177mph in Performance Vorsprung versions - speeds better suited to German autobahns than UK roads.Audi sold 111,115 cars in the UK last year, 28 per cent of them electric.Audi UK director José Miguel Aparicio said: 'As the first high-performance plug-in hybrid, the RS 5 marks the beginning of a new era for Audi Sport. It takes usability, performance and excitement to a new level.' CARS & MOTORING: ON TEST