The ALPINA philosophy rests on a number of central pillars including effortless performance, abundance of torque, smooth automatic transmissions, an emotional soundtrack and precisely tuned suspensions. This in summary sophisticated driving experience with a sporty touch is perfectly suited for elegant convertibles where an open roof amplifies all sensations. Hence it is not without reason, that BMW ALPINA Convertibles based on the BMW 4 Series have a small and particularly loyal group of enthusiastic owners who share a passion. The new BMW ALPINA B4 S Bi-Turbo Convertible carries on this legacy with its impressive performance, driving dynamics and elegant silhouette.
The design of the BMW ALPINA B4 S Bi-Turbo Convertible is characterized by short overhangs, precise, long-drawn-shoulder lines, a wide rear and the characteristic metal folding roof. The sporty and purposeful design of the front spoiler is dictated by functional air intakes and operates in conjunction with the modest rear spoiler to improve stability at high speeds. When the roof is open the BMW ALPINA B4 S Bi-Turbo Convertible stands out with its sleek, clean look. The ALPINA CLASSIC 20″ light alloy wheels fit seamlessly into the overall shape of the Convertible and lend it a particularly elegant presence.
It only takes 20 seconds and the press of a button to close the roof, which is possible up to a speed of 18 km/h, turning the Convertible into a winter- and weather-proof two-door. The shape of the roof line when closed differs from the BMW ALPINA B4 S Bi-Turbo Coupé significantly due to the steeper rake of the rear windscreen, the flat boot lid and subtle rear spoiler – this gives the Convertible a very distinctive and stand-alone appearance.
The design of the BMW ALPINA B4 S Bi-Turbo Coupé combines muscular and delicate elements in one chic silhouette. The Coupé is longer, wider and significantly lower than the Saloon. Its profile rakes from an imposing, muscular front accentuated with bold lines to a clean and stylish rear. The front spoiler, with subtle ALPINA lettering, integrates seamlessly into the dynamic front apron which is characterised by large air intakes for the cooling system of the turbo-charged engine, the transmission and the high-performance fixed-calliper brake system. Together with the rear spoiler the Coupé’s aerodynamics are optimised for excellent high-speed stability while simultaneously maintaining a low drag coefficient. It is almost as if the low, elongated silhouette of the Coupé was shaped to complement the 20″ ALPINA CLASSIC wheels. Their timeless, twenty spoke design with hidden air valves suit the BMW ALPINA B4 S Bi-Turbo exceptionally well. Blue brake callipers with ALPINA lettering and signature twin tailpipes complete the appearance.
The output of the 3.0 litre straight-six cylinder engine with high-precision direct injection and Valvetronic has been further increased with the aid of a revised turbocharging system comprising two new ALPINA specific turbochargers and a new high-performance cooling system. The BMW ALPINA B4 S Bi-Turbo now delivers 324 kW (440 hp) between 5500 rpm and 6250 rpm and a maximum torque of 660 Nm between 3000 rpm to 4500 rpm. In fact, 600 Nm of torque is available across an even broader range from 2000 rpm to 5000 rpm!
The new engine particularly impresses in the mid-range with an effortless power delivery in addition to an eager willingness to rev to 7000 rpm. Coupled to the excellent ZF 8-Speed Sport-Automatic Transmission it propels the new BMW ALPINA B4 S Bi-Turbo Coupé in just 4.2 seconds (Convertible: 4.3 seconds) from 0 to 100 km/h and on to a top speed of 306 km/h (Convertible: 304 km/h). With the traction advantage provided by having such high power output transmitted to four wheels, the new BMW ALPINA B4 S Bi-Turbo Coupé AWD accelerates even faster, taking just 3.9 seconds for the sprint from 0 to 100 km/h. BMW Efficient Dynamics technologies such as Auto Start Stop and Sailing contribute to an exemplary fuel consumption of between 7.9 l – 8.3 l/100 km and 180 – 190 g/km CO2 combined measured to ECE norm, depending on the model.
To achieve the BMW ALPINA B4 S Bi-Turbo’s characteristic, torque driven and spontaneous power delivery without sacrificing fuel efficiency necessitates state-of-the-art engine technology in a clever package. The application of Bi-Turbo charging provides excellent throttle response and pick-up due to the low mass inertia of smaller turbocharger running gear while generating sufficient throughput for top-end performance. The design and construction of the excellent BMW 3.0 litre straight-six cylinder (N55) engine serves as a starting-point for a specially cast aluminium crankcase with reinforced bed plate and Bi-Turbo capable flanges. The latter facilitate the mounting of two turbochargers along with their oil and water feeds and a close-coupled catalytic converter arrangement. This latest iteration of the 3.0 litre straight-six cylinder engine receives new ALPINA specific turbochargers for even more output and a new piston crown cooling system. ALPINA air intake ducts guide the air with minimal losses from the air intake via the air filter housing to the turbochargers. A high-capacity intercooler with optimised collector boxes made from aluminium allows the full exploitation of the engine’s output potential. The high-performance cooling system has been further adapted concordant to the latest increase in engine output – the external water cooler and external oil cooler have grown in capacity by more than 15 % and 35 % respectively.
A stainless steel exhaust system, developed in collaboration with Akrapovic, features two trademark elliptical twin tailpipes which are elegantly integrated into the rear valence. The resonant, sporty sound of the exhaust system is controlled by an intelligent exhaust valve. This offers the driver the possibility to influence the sound experience via the Drive Experience Control and facilitates the balancing act between emotional soundtrack and long-distance comfort. In Comfort Mode the exhaust valve remains closed up to 2500 rpm, beyond which it opens depending on engine load and rpm. In Sport Mode, however, the valve is permanently open and the BMW ALPINA B4 S Bi-Turbo thrills with an emotional soundtrack.
The stainless steel exhaust system which was developed in collaboration with Akrapovi saves 7.5 kg of weight. The resonant, sporty sound of the exhaust system is controlled by an intelligent exhaust valve. This offers the driver the possibility to influence the sound experience via the Drive Experience Control button and facilitates the balancing act between emotional soundtrack and long-distance comfort. In Comfort Mode the exhaust valve remains closed up to 2500 rpm, beyond which it opens depending on engine load and rpm. In Sport Mode, however, the valve is permanently open and the B4 S Bi-Turbo thrills with its distinctive aural character under hard acceleration – when additionally selecting Sport (S) or Manual (M) Shift Mode the exhaust will deliver an occasional burble on the overrun.
2018 Alpina BMW B4 S Bi-Turbo Front View 3/4
Inspired by the pleasure that the 8-Speed Sport-Automatic Transmission with SWITCH-TRONIC offers in the larger V8 powered BMW ALPINA models, the so-called 8HP70 transmission has been extensively adapted to suit the performance characteristics of the BMW ALPINA B4 S Bi-Turbo models. Hardware modifications to ensure that maximum possible power delivery can be achieved include reinforced front and rear axle differentials, high-strength output and drive shafts and a high-torque transmission gear unit. In actual fact, the high power output and torque of the Bi-Turbo combine so well with this transmission that performance figures usually associated with much larger but less efficient engines are achieved. Furthermore, this transmission excels in disciplines often assumed to be incompatible and offers an optimum driving experience in every situation. To this end, three shift modes are available: Automatic (D), Sport (S) and Manual (M).
In Automatic (D) Shift Mode the focus is strictly on driving comfort. The transmission changes gears quickly and with no noticeable interruption to the delivery of power. The torque of the engine enables consumption-optimised ‘surfing’ in high gears even at very low speeds and in urban driving environments. Even at higher cruising speeds the rpms will remain low, for example 2500 rpm at 170 km/h in 8th gear, increasing long-distance driving comfort significantly.
Sport (S) Shift Mode noticeably shortens the time it takes for the next gear to engage and depending on engine load significantly moves the shift points up the rev range.
Accelerator inputs are carried out immediately, full throttle i.e. kick-down will implement multi-simultaneous downshifts and optimal acceleration. When combined with the Sport or Sport+ setting of the Drive Experience Control, which modifies the drive and chassis setup, gearshifts are even quicker.
Activating the Manual (M) Shift Mode using the SWITCH-TRONIC buttons on the back of the steering wheel, allows the driver to take control and shift gears when suitable or necessary. A special feature of the Sport+ and DSC Off setting is the suppression of automatic up-shift in Manual (M) Shift Mode – hereby the selected gear is held into the rpm limiter and the transmission will not up-shift into a higher gear.
High torque allows the use of a long rear axle ratio which in combination with the 8-Speed Sport Automatic Transmission and Auto Start Stop contributes significantly to achieving great fuel economy. Top speed is achieved in 7th gear.
SUSPENSION & CHASSIS
The suspension set-up of the BMW ALPINA B4 S Bi-Turbo provides great ride-quality and comfort while simultaneously offering sharp and dynamic handling. The adaptive ALPINA sport suspension solves this conflict of interest by means of electronically adjustable dampers in collaboration with performance springs, bump stops and stabilisers. The system allows the driver to use the Drive Experience Control (Eco Pro, Comfort, Sport, Sport+) to select the suspension setting and driving dynamics to match his mood.
The longer wheelbase and wider track at the front and rear provide the BMW ALPINA B4 S Bi-Turbo Coupé with a more dynamic character from the outset. Subtle adjustments to camber, toe-in and elastokinematics result in a neutral chassis and very balanced handling. The 20″ ALPINA CLASSIC wheels with MICHELIN Pilot Sport 4 S tyres combined with a front strut brace accentuate the Coupé’s direct and precise turn-in.
New ALPINA CLASSIC 20″ forged wheels with revised, minimalistic design. A reduction in unsprung mass results in even sharper handling and precise steering and also leads to enhanced comfort.
The Drive Experience Control settings also influence other parameters which effect driving dynamics, such as the electric power steering and the driving stability control (DSC and DTC) system. The latter is subject to a software coding which takes into account the specifics of the ALPINA suspension and chassis.
The Variable Sports Steering from BMW, which comes as standard, has a progressive steering rack providing steering stability at high speeds but which requires significantly less steering input (turns of the wheel) when manoeuvring and parking.
Deceleration is taken care of by an 18″ high-performance brake system with 370 mm discs at the front and 345 mm discs at the rear. Aluminium callipers (4-piston on front axle, 2-piston on rear axle) painted in blue and with ALPINA lettering, in conjunction with high-performance pads, ensure fading stability and optimal pedal feedback.
Available on the BMW ALPINA B4 S Bi-Turbo Coupé, the optional all-wheel drive (not available in RHD markets) system offers even more traction and active safety in every and any driving situation. It exploits the technical potential of BMW’s xDrive system and its intelligent and dynamic distribution of drive power which continuously and fully variable distributes torque between the front and rear axle within milliseconds.
The torque distribution algorithm communicates with the ALPINA DME and the adaptive suspension system to increase driving dynamics and agility, particularly during high lateral acceleration, creating unexpected sporty and neutral handling despite all-wheel drive. Besides ensuring optimal traction during acceleration, the system also permanently monitors a wide range of sensory inputs – for example steering angle, lateral acceleration, yaw angle and speed – to distribute torque so as to achieve optimum propulsion and safety for example on snow or to counteract sudden changes in road surface friction.
DESIGN & EQUIPMENT
The BMW ALPINA B4 S Bi-Turbo models come with an extensive list of standard equipment, including leather upholstery, electrically adjustable heated sports seats, automatic climate control, xenon headlights, rain sensor and cruise control. The interior is dominated by refined materials and offers an exclusive ambiance. The door sills, floor mats, emblems in the seatbacks, instrumentation and a hand-stitched sport steering wheel in the finest LAVALINA leather make discreet references to the car’s exclusive origins.
Virtually no limits are placed on the individual design of a BMW ALPINA. From the paintwork to the interior trims and the colour of the upholstery – everything offered by the extensive BMW and ALPINA equipment range is available. Seldom does a BMW ALPINA leave the plant in Buchloe without making use of the virtually limitless personalisation options offered by the ALPINA factory. ALPINA philosophy dictates that the customer can design his or her own entirely individual interior – assembled by skilled craftsmen in our leather workshop.