The 2011 Honda CR-Z: a two-seat sports car for the environmentally minded: it’s a hybrid.
The CR-Z features a 1.5-liter engine mated to the Integrated Motor Assist (IMA) system. Combined, the engine and the electric motor produce a peak output of 122 hp @ 6,000 rpm and 128 lb-ft of torque @ 1,000 to 1,750 rpm on the six-speed manual models and 123 lb-ft @ 1,000 to 2,000 rpm on CVT-equipped cars.
To assure that the CR-Z has a highly rigid structure, extensive use is made of high-strength steels.
The large project leader—or chief engineer—of the 2011 Honda CR-Z is Norio Tonobe. When talking about the two-seat hybrid-powered sports car, he mentions, in passing, that he saw the program as a way to “revitalize Honda.” While Honda has been more than holding its own in the U.S. market and doing comparatively well elsewhere, it is almost as though the CR-Z—which is certainly an heir to the CRX models from 1984 to 1991 (two generations)—speaks to the engineering capabilities of the car in a way that it seems only Honda can do. That is, here is a small, stylish car with a powertrain—a 1.5-liter, 4-cylinder, 16-valve i-VTEC gasoline engine combined with a 10-kilowatt, ultra-thin electric motor (electricity is stored and delivered through a lightweight and compact 100.8-volt battery and power control system)—that is technically sophisticated, yet will come in its fully loaded version (CR-Z EX with Navigation) under $24,000. What other vehicle manufacturer would do that, particularly in light of the fact that American Honda sales people project overall U.S. sales of the vehicle to be only around 15,000 per year? (Although it should be noted that this is a global vehicle and that in its first four months of availability in Japan there were 20,000 sold.)
Tonobe talks about how he focused creating a light-weight, agile-handling car, a “café racer”: a car of the type that people talk about after driving at the local Starbucks; a type of car that is fast, also addresses CAFE concerns—it is rated AT-PZEV and Tier 2 Bin 2; the version with a continuously variable transmission provides fuel economy of 35/39/37 mpg and the model with the six-speed manual turns in 31/37/34 mpg. Note that it is doubtless that they could have engineered the car to be more fuel efficient, but that would miss the point of creating the café racer. They worked at developing a two-seater that is economical and ecological, but not a bowl of bran flakes.
While there is some sharing with the Honda Insight hybrid—a four-door—like the fundamental Integrated Motor Assist (IMA) parallel hybrid system (the electric motor supplements the internal combustion engine, although this is the sixth gen of the IMA, and has some modifications, such in cooling, that have been made to it for this application) and some of the frontal understructure, the sharing was done to reduce costs through increasing volume. But whereas the Insight has a 1.3-liter two-valve per cylinder engine, the CR-Z’s is a 1.5-liter, four-valve per cylinder car.
Combined, the gasoline engine and electric motor for the CR-Z produce a peak output of 122 hp @ 6,000 rpm and 128 lb-ft. of torque @ 1,000 to 1,750 rpm on manual transmission models (123 lb-ft @ 1,000 to 2,000 on CVT-equipped models). Individually—but it runs as a system, so there really is no separation—the gasoline engine produces 113 hp (84 kW) @ 6,000 rpm and 107 lb-ft. of torque @ 4,800 rpm. Then there’s the electric motor, which can provide 13 hp @ 1,500 rpm and 58 lb-ft of torque @ 1,000 rpm. Note the broad power curve that is provided via having different peak output points for both the engine and the motor, said to be wider than can be achieved by a stand-alone internal combustion engine of the same size or a comparable full electric vehicle.
The CR-Z, Tonobe says, was specifically designed to be low, short and wide. One interesting consequence of this was that it was necessary to redesign the engine intake manifold so that it was short enough (by 10 mm) to fit under the low-slung hood. What’s more, particular focus was placed on making the structure stiff, which meant the extensive use of 780- and 980-mPa steel (e.g., for front pillar inner lower, side sill, middle floor cross member) and design elements such as closed cross-section structures both in the front bulkhead and the tailgate circumference. (The Honda Advanced Compatibility Engineering body structure is used for both occupant protection and crash-compatibility in front-end collisions; it is also designed with pedestrian crash mitigation in mind, with such things as the hood being designed to deform in contact with a pedestrian and energy-absorbing fender mounts and supports.) And there was focus on making the car as light as possible (things like nickel-metal hydride batteries add weight), so there is the use of aluminum on the chassis (e.g., a cast aluminum lower arm).
Similarly, there was focus on the overall aero of the vehicle, and they managed to achieve a coefficient of drag of just 0.30. One of the challenges the engineers faced was the comparatively short length of the car, 160.6 in. Longer cars have an advantage in that there is greater area to control the flow of air. So in the case of the CR-Z, the designers and the engineers worked to achieve the longest length roof possible, with aesthetic and functional considerations balanced. In addition to which they made sure that there was controlled airflow at the rear of the vehicle, as well as doing such things as put spoilers, engine under covers, strakes, and other aero elements on the car.
Inside, the CR-Z has high-quality materials, including Honda’s first-ever use of metal evaporative coating of the door grips and on the center stack. A metal film is created, then vacuum formed on the part surfaces so that there is adherence to the contours. Also, the top of the instrument panel is Honda’s first use of reaction injection molding (RIM) for the application; it provides a soft-touch surface and high contour fidelity. The skin is just 1-mm thick.
Whether it meets its target buyer—the college-educated single from 25 to 35 years old—remains to be seen. Chances are, there will be greater appeal among those with fond remem-brances of the CRX, especially the second-gen model.—GSV