Saturday, March 16, 2013

News: Consumer Reports and the fuel economy of small turbocharged engines

Last month, Consumer Reports released a scathing piece on how small turbo-charged engines are not living up to their claimed fuel economy numbers. Many manufacturers have turned to the smaller displacement engines and bolting on the compressors in an effort to offer 6-cylinder levels of performance with 4-cylinder levels of fuel economy. The recent jump in the number of turbo-charged options has been a great boon for automotive enthusiasts offering great claimed horsepower numbers in conjunction with shockingly good claimed fuel economy.  However, the big caveat here is that we can only fiddle with the physics so much and the narrowly defined band of efficiency is difficult to maintain in even the most ideal driving conditions.

Internal combustion motors work by converting the energy of burning a mixture of fuel and and air into motion. Add more air to the equation and you will absolutely need to add more fuel in order to maintain the optimal air-fuel ratio to get the best burn. Add in the fact that most turbo-charged motors require either a lower compression ratio, thus reducing power output when no boost is being applied, or direct injection in order to offer higher compression ratios, the number of variables to control goes up quite a bit. It should come as no surprise that there is going to be some sacrifice in efficiency if we are relying on the boost to help generate the higher performance numbers. Mix in the American tendency to get heavy on the throttle and the general lack of discipline in traffic conditions and the fact that these cars are not living up to their claims in real world driving conditions.

Nonetheless, even if this is not the best answer to our desires for the combination of power and efficiency, it is a starting point and offers a place from which we can learn how to further improve our efforts. If you have one of the cars on the list that Consumer Reports tested, please share with us your experience.


Read the original new release here.