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Outstanding Performance, Maximum Efficiency

The drivetrain of the D5 Bi-Turbo utilizes the excellent attributes of the BMW full aluminum 3 liter in line six cylinder engine with modern common-rail direct injection and two turbochargers with variable turbine geometry.

With the aim of further maximizing the potential of this engine and using the freedom that small series production allows, the engineers from Buchloe have worked extensively on optimizing the air intake flows. The new air intake ducts have substantially larger diameters and feature optimized radii which lead to a 30% reduction in loss of pressure. This effective means of 'de-restricting' the air flow between the air intake and the air filter housing allows the engine to breathe more freely, resulting in improved performance and a more lively character. In combination with the realization of appropriate turbo charging and injection pressures this leads to a maximum output of 350 hp (257 kW) between 4000 rpm - 4200 rpm.

The performance and effectiveness of the entire cooling system has a direct influence on the stability and output of turbo charged engines - as a result, the cooling system in the new D5 Bi-Turbo is of central importance. A large volume (charge-air) intercooler (+20%), with an optimized inlet and outlet design, feeds the engine with air. Two additional separate water coolers, which are situated in front of the wheelhouse and lie perfectly within the air flow from the front spoiler, ensure that all cooling mediums (via oil/water-heat exchangers) are kept at optimum temperatures, even during maximum thermodynamic loads. The operating parameters and components of the cooling system are managed by a cooling system control unit which features an intelligent operation of the electric cooling fan to directly influences performance under full loads.

An exhaust manifold made from high-strength D5S material allows for higher exhaust gas temperatures (+50°C) which result from the increased power output. The exhaust system is principally a carry-over from the B5 Bi-Turbo but includes a diesel particulate filter. Sound engineering and the reduction of silencer volumes has resulted in a for diesel engines surprisingly throaty exhaust sound, especially at higher rpms. The character of the engine overall is unusually lively for a diesel engine, revving freely and convincingly past 4500rpm.

Despite the engine's high specific power output of 117 hp per liter, it achieves class-leading fuel consumption and emission figures: 6,2 l/100 km (45.6 mpg) and 165 g/km CO2 (Touring: 6,5 l/100km (43.5 mpg) and 172 g/km CO2) (Combined, measured according to ECE norm).

Eight-Speed Transmission

Adapted and tested in co-operation with ZF, the advanced SWITCH-TRONIC 8-speed Sport Automatic Transmission features specific hardware modifications demanded by the high torque output, these include special mechatronic components and a different torque converter.

Alpina engineers have spent many development and test hours working on the transmission software to ensure that the transmission provides unparalleled levels of both comfort and performance. The blend of eight speeds and high levels of torque makes for super comfortable gear changes with no noticeable interruption to the delivery of power. In Automatic (D) Shift Mode the D5 Bi-Turbo excels at cruising along at speeds in high gears at minimum rpm, this benefits both consumption and comfort.

Using the Sport (S) Shift Mode the transmission becomes noticeably 'crisper' and unmistakably immediate, gear changes become quicker and take place at higher shift points. The Alpina SWITCH-TRONIC buttons, which are ergonomically and unobtrusively positioned on the back of the steering wheel, activate the Manual (M) Shift Mode which allows the driver to take complete control of the transmission.

The system also allows for multisimultaneous down-shifts in milliseconds, hereby the transmission will skip several gears depending on engine loads and rpm. In this manner the 8-speed Sport Automatic Transmission with Alpina SWITCH-TRONIC reveals itself as extremely multi-faceted, providing the right shift characteristic for any and all situations. It also features an adapted version of BMW's new ECO PRO Mode, which activated via the Drive Performance Control button, puts both the transmission and accelerator into a defensive setting, which in combination with other Efficient Dynamic technologies (including Auto Start Stop) can lead to a reduction in consumption and emissions, depending on individual driving style.

The intelligent coupling of state-of-the-art engine and transmission technologies allow the D5 Bi-Turbo Saloon to achieve impressive performance figures: 0-60 mph in 5 s, and a top speed of 168 mph (270 km/h). Excellent braking capability is provided in the form of ventilated high-performance brakes measuring 374mm front and 345mm rear.

Dynamic Comfort

The times when overly stiff suspensions were seen as a positive handling characteristic are long gone. It remains a fact that a truly neutral set-up, even at the limit, provides the best technical compromise. This is achieved in part through shorter Alpina springs, greater camber at the front and subtle changes to the toe-in. Together with 20" wheels and tires this yields a very balanced and direct chassis set-up, discarding a pure sport-orientated approach for an agile suspension with precise turn-in. Mounted on the light-weight Alpina CLASSIC wheels are non-run-flat MICHELIN PILOT SUPER SPORT tires measuring 255/35 ZR20 front and 285/30 ZR20 rear. Representing the latest in ultra-high performance tire technology available today, they feature a running surface is made up of 2/3rds soft compound (centre) and 1/3rd hard compound (outside and flanks). This mixture makes for excellent durability despite typical hard use in high-performance vehicles yet provides very good grip in the wet. Enhanced tread stability and a new flank reinforcement technology ensures the tire is less likely to suffer from spikes in temperature with a resulting loss of grip in the dry.

To fulfill the seemingly contradictory demands for comfort, everyday usability and dynamic handling, the D5 Bi-Turbo is equipped with electronically-adjustable dampers (Drive Performance Control). This system has been artfully calibrated by Alpina, and is tied into other system parameters controlling steering assistance, torque cushioning and the Dynamic Stability Control system. Featuring pronounced Comfort+, Comfort, Sport and Sport+ settings, the D5 Bi-Turbo transitions effortlessly from cultivated luxury to thorough-bred sportiness. Light steering, ultra-comfortable suspension and an imperceptibly shifting transmission make the D5 Bi-Turbo an ideal partner in stop-and-go traffic, when covering great distances or when encountering less than perfect road surfaces. Yet at the touch of a button, the D5 Bi-Turbo will track through tricky corners and along exciting sections of road with an agility and light-footedness like no other in its class.

BMW Alpina D5 Bi-Turbo: Photo Gallery, Review (1/2) and Specifications