Automotive

Reliability is up.  And the bottom structure of this car is now all aluminum with aluminum double wishbone front axle suspensions.  Compared to the multi-link strut suspension and steel subframe, this is a remarkable improvement.  Double wishbones are especially nice because they keep the tire in better contact with the road, maximizing grip.  The negative of Double Wishbone is that they take up more space than a traditional MacPherson strut set up (what BMW used to use) and thus packaging and design costs go up.  The actual component cost at the manufacturer level for Double Wishbone isn't significantly more expensive (since manufacturers can buy in bulk quantities).  Also, Double Wishbone physically takes up more space, which means less under-the-bonnet space for the front and less trunk space for the rear (assuming your trunk is in the rear).  Suspension parts are often made in steel as this is very reliable and cost effective.  However, the weight of the steel dampens the car's motions, and the unsprung weight has its own intertia gravity, which reduces the immediacy of the car's dynamism.  Thus, aluminum is advantageous as it's light.  The disadvantage of aluminum is that it's more easily damaged and more weakened when damaged than steel, thus an aluminum set up would not be favored in an SUV that would do true off-road duty.  An off-road SUV would use steel that is less easily damaged and can theoretically still retain most of its strength even after being slightly bent from hitting a rock. 

Now, why am I singling out BMWs specifically?  BMW has really made a big emphasis on suspension design and improved powertrain reliability over the years (especially with the 3.0 liter I6 B58 engine).  The 5, 7, and 8 series are all class leaders- aluminum intensive suspension and body structures and from the smallest engine to the largest one.  Comparing the Mercedes E63 AMG to the BMW 530i 2.0 liter, the E63 has a rear steel subframe and mostly aluminum linkages - compared to the BMW which has virtually all aluminum subframes and aluminum linkages on the base 2.0 liter engine.  The bottoms of the BMW wouldn't look much different compared to a Ferrari sports car (Ferrari sports cars are very aluminum intensive).  Even Porsche uses a MacPherson strut set up and not a Double Wishbone!  Way to go BMW!  

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