According to reports in auto blogs like Worldcarfans and Automotive News, the 2015 Mustang may weigh as much as 300 pounds more than the 2014 model. The weight gain is being attributed mainly to the switch from a live solid rear axle to independent rear suspension.
However anyone with knowledge of automotive technology would find it difficult to believe switching from a solid rear axle to independent rear suspension could add 300 pounds to the Mustang’s weight.
Other sources with knowledge of Mustang architecture say Ford wanted to improve roll over safety, so they added steel to the structure of the body to better meet the federal government’s recently toughened rollover guidelines.
Thus the increase in weight is likely a combination of the switch to independent rear suspension and increased structural strength to meet new government safety standards.
Weight hurts performance
When a vehicle gains weight the effect is multiplied throughout all the vehicle’s systems. More weight obviously means the engine must work harder to accelerate the vehicle, which reduces performance and increases fuel consumption. Increased weight also means springs need to be heavier, the tires wear more and the brakes, steering and suspension components need to be stronger.
Is 300 pounds meaningful?
Every time you pull away from a stop light, that's 300 extra pounds the engine has to overcome as the vehicle accelerates. Every time the driver hits the brakes, that's 300 extra pounds the brakes have to bring to a stop. Look at it another way: You go to the drag strip on Sunday but you lose by a half second. After the race you discover your kids put 300 pounds of Silly Putty in your trunk.
Reduced weight = free horsepower
On the other side of the equation, reducing a vehicle’s weight by 300 pounds is like getting a free horsepower boost. The vehicle will accelerate faster, stop quicker, handle better through turns and use less fuel along the way. Springs, brakes, suspension and tires don't have to work as hard because there’s less weight to deal with.
Ford CEO Allan Mulally is on record as being committed to reducing the weight of the Ford fleet. Ford has gotten favorable publicity as a result of an aggressive weight reduction program with the 2015 F-150 Pickup which uses aluminum body panels to reduce the F-150's weight by as much as 700 pounds.