The 2010 X5 continues with a choice of three powertrains � two gasoline and one diesel. The gasoline-power choices include an inline 6-cylinder (X5 xDrive30i) or a V-8 (X5 xDrive 48i) engines: both providing performance and excellent efficiency. The flagship 48i boasts BMW�s all-aluminum Valvetronic V-8, with 350 horsepower. The 30i features BMW�s aluminum/magnesium inline-6 rated at 260-horsepower. Introduced last year, the X5 xDrive35d features BMW�s sophisticated 3.0-liter sequential twin-turbo inline 6-cylinder diesel. This 50-state compliant engine produces 265 horsepower and a stunning 425 lb-ft of torque. Standard equipment on all three models is a 6-speed STEPTRONIC automatic. BMW�s outstanding xDrive all-wheel-drive system continues, enhanced via a closer link between the xDrive electronics and the X5�s Dynamic Stability Control to provide even quicker, more accurate response.
The X5�s front suspension represents a break from a 45-year-old BMW tradition: It�s a double wishbone multi-link design with upper A-arms combined with double-pivot lower links�the first non-strut design since 1961. The company�s departure from its traditional dual-pivot strut front suspension was dictated by customers� increasing expectations for ride and handling. Combined with a longer wheelbase, wider track and BMW�s revised 4-link Integral rear suspension, the new front design sets new standards for on-road ride and handling, as well as improved all-road ability. In keeping with its original mission, the X5�s focus still places more emphasis on pavement performance, keeping it well abreast of the competition.
The new X5 xDrive35d: power, torque and remarkable fuel efficiency. All with refinement and performance worthy of a BMW.
In Europe, where fuel prices have historically been � and remain � much higher than in the U.S., vehicle manufacturers have achieved dramatic gains in the performance, smoothness, quietness and emission control of diesel engines�while maintaining the diesel�s historic superiority in fuel efficiency. Last year the BMW X5 xDrive35d brought this progress to the U.S., with brand-new technology that meets the emission standards of all 50 U.S. states.
Like all BMW gasoline engines, the X5�s diesel is constructed with a weight-saving aluminum cylinder block � something that�s not taken for granted given the diesel�s much higher compression pressures. (All BMW engines have aluminum cylinder heads.) It is an inline 6-cylinder engine maintaining a defining BMW tradition that means exceptional smoothness and unique sound.
In addition, several diesel-specific technologies of this new engine contribute to its achievement of true high performance, diesel fuel economy and clean exhaust:
Common-rail direct fuel injection. One of the most important innovations of recent diesel development, this has replaced the individual-cylinder or distributor-type injection systems of earlier diesel engines.
Common Rail (CR) means that a single, very high-pressure fuel-delivery pump supplies all cylinders, the fuel traveling along a common �rail� or distributor line. From there, fuel is injected at extremely high pressure (180 bar/2645 lb./sq in.) directly into the cylinder.
The basic novelty of common-rail injection was to divorce the production of fuel pressure from the actual injection process; this was necessary to give the diesel engine what gasoline engines have long had, namely completely electronically controlled fuel injection. CR also facilitates multiple injections per combustion cycle. In all, this was a breakthrough that made possible dramatic strides in diesel power, efficiency and emission control.
Piezo injectors. A further breakthrough, already applied by BMW in other models� twin-turbo gasoline engines. With direct injection, the injectors � that critical component injecting fuel into each cylinder�s combustion chamber � are subject to especially high temperatures and pressures. Instead of most injectors� conventional electrical valves, a �stack� of piezo crystals reacts lighting-fast to impulses from the engine electronics governing the injector needle�s opening stroke and duration for ultra-precise control. This, too, facilitates major advances in fuel economy and emission control, in gasoline, as well as diesel engines.
Sequential Twin Turbo technology. In contrast to the two small, equal-size turbochargers of BMW�s twin-turbo gasoline engines, the diesel employs two turbos of different sizes.
At low engine speeds, intake air does pass through the large turbo, but it�s the smaller, lower-inertia one that does the air compressing (turbocharging). Thanks to its optimum efficiency within this rpm range, it provides effective boost for driving from a standstill up to modest acceleration rates and driving speeds. So it is that this engine develops a good 390 lb-ft. of torque at as low as 1500 rpm � a remarkable achievement that will amaze first-time X5 xDrive35d drivers and continue to thrill those who drive this BMW regularly.
With increasing engine speed, the larger turbocharger begins to take over: first as a pre-compressor for the smaller one, then progressively until it becomes the primary turbo. The engine reaches its maximum of 425 lb-ft. by 1750 rpm, then maintains this immense torque level until 2250 rpm going on to reach its peak power of 265 hp at 4200 rpm.
Diesel combustion, power and torque characteristics. In its most basic distinction from gasoline engines, a diesel engine achieves its combustion not with a sparkplug, but by much �harder� compression of the fuel-air mixture; the X5 xDrive35d engine, for example, has a compression ratio of 16.5:1, vs. 10.7:1 and 10.5:1 in the gasoline engines of the X5 xDrive30i and 48i, respectively.
The diesel combustion process also produces very different torque and power characteristics. For example, the 48i�s V-8 engine reaches a maximum torque of 350 lb-ft. @ 3400 rpm and a maximum power of 350 hp @ 6300 rpm, while the six cylinder engine of the 35d attains its maximum torque of 425 lb-ft. @ 1750-2250 rpm and its maximum power of 265 hp @ just 4200 rpm. In general, diesels have this low-speed-torque, lower-rpm character and in their vehicular application, they are geared differently. As such, an automatic is the ideal partner for a diesel engine.
Diesel engines also employ a different fuel, the product of a different refining process from that of gasoline. The two fuels are not interchangeable; gasoline cannot be used in a diesel engine and vice versa. Their prices typically diverge; at any time or in any location, demand may be different for the two, and government taxation policies for gasoline and diesel fuel also diverge.
Stellar pulling moxie, full-bore acceleration � and fuel efficiency. The huge torque output of 425 lb-ft. at relatively low engine speeds speaks for itself; X5 xDrive35d drivers will marvel at this engine�s robust response at low to medium speeds. The peak power output of 265 hp also speaks for itself, as does the resulting 0-60-mph time of 6.9 seconds. That is only a half-second slower than the V8 X5 xDrive48i. In spite of its responsiveness, it returns EPA mileage estimates of 19 mpg city and 26 highway.
Most advanced exhaust gas management: SCR catalyst with AdBlue injection.
BMW Advanced Diesel with BluePerformance optimizes emission management by incorporating an oxidation catalyst placed close to the engine, a diesel particulate filter housed in the same unit, and an SCR catalyst with urea injection. Apart from filtering out even the smallest particles from the flow of exhaust gases, this combination ensures effective reduction of nitric oxides (NOX) by way of a chemical reaction within the exhaust system initiated by the injection of a small dose of urea referred to as Diesel Exhaust Fluid. Into the exhaust stream. The ammonia (NH3) generated in this process within the SCR catalyst subsequently converts the nitric oxides (NO and, respectively, NO2) in the exhaust gas into environmentally compatible nitrogen (N2) and water vapor (H2O).
BMW has developed a two-tank system for DEF ensuring convenient use of this new technology with all the benefits and ease required by the customer: The amount of DEF required in each case is drawn from the active tank comprising approximately 1.6 gallons by means of a dosage pump. And since the urea solution would freeze at a temperature of -11oC, this active tank, as well as the dosage pipes are heated.
BluePerformance technology by BMW: reduced emissions without additional service appointments.
The active tank is connected to a second reservoir, the so-called passive tank. With its additional capacity of approximately 4.5 gallons, this passive tank offers a plentiful supply of the urea solution required within the SAV. The average range provided on this supply capacity is indeed sufficient to have the tank system replenished as part of normal scheduled maintenance.
