When GM announced an "Eco" version of its Chevrolet Cruze tweaked for fuel efficiency, it said that it was aiming for an EPA rating of 40 MPG on the highway, a respectable figure for a car that isn't particularly small, that meets modern safety standards, and is rated under the stricter EPA methodology (don't compare it to your 20 years old Geo Metro, please). But now that the EPA rating is out, the Cruze Eco actually does better than what it was aiming for, with 42 MPG highway/28 MPG city.
How did it do it? With the following tricks, which should be used on all cars and not just on special "Eco" models. The info below comes from GM:
Aerodynamic improvements over non-Eco manual-transmission models contributed approximately six mpg to the Cruze's EPA-estimated 42 mpg highway fuel economy. Many were developed and refined in more than 500 hours of wind-tunnel testing of the Chevy Volt, which shares a core architecture with the Cruze. Examples include the upper grille, which has more "closeouts" to improve aerodynamics, a lower front air dam extension, a rear spoiler, a lowered ride height and underbody panels that smooth airflow beneath the car.
The Eco model also features an all-new technology in the compact segment: a lower front grille air shutter that closes at higher speeds to reduce aerodynamic drag and opens at lower speeds to optimize engine-cooling airflow. Another contributor to reduced drag is the use of ultra-low rolling resistance 17-inch Goodyear tires (used with lightweight wheels), which are also used on the Volt.
As a result of the aero enhancements, aerodynamic drag was reduced by 10 percent over a non-Eco model, with a coefficient of drag of 0.298. That places Cruze at the top of the class for mainstream compact cars.
More than 42 changes were made on the Eco to reduce weight. It weighs in at 3,009 pounds (1,365 kg), compared to the 3,223 pounds (1,462 kg) of the Cruze 1LT.
Cruze Eco is powered by power-dense Ecotec 1.4L turbocharged engine and a standard six-speed manual transmission. The transmission's gearing is optimized for the model's specific 17-inch wheel/tire combination and includes aggressive ratios for first and second gear coupled with a highly efficient, "taller" sixth-gear ratio for highway driving. That means engine rpm is reduced on the highway, which in turn reduces fuel consumption. A six-speed automatic transmission is available, with EPA-estimated fuel economy ratings of 26 city and 37 highway.
The Ecotec 1.4L turbo's power ratings are 138 horsepower (103 kW) and 148 lb.-ft. of torque (200 Nm) between 1,850 rpm and 4,900 rpm. The wide rpm range for the maximum torque - a specific trait of turbocharged engines - helps the engine deliver a better driving experience and performance. The turbocharger is integrated within the exhaust manifold, for reduced weight and greater packaging flexibility.
We Need a Fuel Efficiency Arms Race
Now let's hope that competition will do the rest and that other automakers will come out with cars that do 46 MPG on the highway and 32 in the city, and then the next round can go higher than that and so on...
It's still much better to walk, bike, or take public transit. But if you have to drive, get the most fuel-efficient vehicle that fits your needs and drive it as sanely as possible (learn hypermiling tricks and use them when appropriate, combine trips, etc).
More on Green(er) Cars
Toyota Unveils the Prius PLUS Performance Package
Toyota is Turning Old NiMH Batteries Into New Batteries
Nissan Launches the Fuga Hybrid in Japan (Coming to US as an Infiniti in 2011)
Volvo to Make Plug-In Diesel Hybrid Based on V60 Wagon in 2012
2011 Hyundai Sonata Hybrid to be Eligible for $1,300 Tax Credit
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