The Cycles of Technology
 
Automotive manufacturers introduce technologies as their products cycle through their launches. A new engine design will be introduced in one model, lightweight suspension components in the next model (which also integrates the new engine design), aerodynamic technology in the next model (which also integrates the new engine and suspension design), and so on.
 
 The engine technology in the new 2012 Impreza is an example. All Subaru models have not been converted to the new design, and it was not introduced first in the Impreza. Rather, it was first used in the 2011 Forester.
 
The same is true of the CVT in the 2012 Impreza. That transmission technology was introduced in the 2011 Outback and Legacy.

Aerodynamic Shapes

 

How a vehicle moves through the air helps determine the amount of fuel that must be used by the engine to overcome drag – friction caused by the air. A measure used by manufacturers that indicates the aerodynamic efficiency of a vehicle’s body is called “coefficient of drag,” or Cd. Multiplying that figure by the frontal area of the vehicle gives a numeric indicator of its aerodynamic drag.

 

A vehicle’s overall shape, the finish of its surfaces, and how air flows through cooling and ventilating systems all affect its Cd, which can be measured in wind-tunnel tests. The lower a vehicle’s Cd, the better it moves through the air, and the better its fuel economy.

 

The accompanying chart indicates the coefficient of drag for 2012 Subaru models. 

 

Coefficient of Drag (Cd)
   
2012 Subaru Models
 
Cd measures aerodynamic efficeiency – the lower the number, the better
   
Impreza 0.31-0.33
Legacy 0.32
WRX/WRX STI 0.34-0.35
Outback 0.37
Forester 0.375-0.382
Tribeca 0.38

Perhaps you’ve never considered the aerodynamic design of a Subaru. Aerodynamics are part of every model, and the emphasis that Subaru puts into the aerodynamics of its products has been reflecting its engineering prowess for years. As an example, in the mid-1980s, Subaru introduced its XT Coupe, which had the lowest Cd of any mass-produced car at that time – 0.29. (See article on the 1986 XT Coupe in Summer 2011 Drive.)

 

The Cd measurements of 2012 Subaru models are not much more than the XT Coupe’s 0.29. All are within 0.10 Cd of it.

 

Along with their smooth exterior shapes, all 2012 Subaru models have aerodynamic underbody panels. These smooth panels cover the bottom of the engine and some driveline and suspension components to help prevent them from disrupting airflow under the vehicle. Front wheel liners and wheel opening aero flaps also aid airflow efficiency.

 

On the 2011-2012 Legacy and Outback as well as the 2012 Impreza, the angles of the windshield have been lowered compared to previous generations. The lower angles promote airflow over the vehicles. The front bumpers on the 2012 Impreza also have an optimized aero shape.

 

 

 

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