Honda bets big on minicars to unlock innovation
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TSUNOMIYA, Japan -- An important yet unsung piece of Honda's comeback plan is a redoubled focus on small cars, really small cars -- the ultramini kei segment peculiar to Japan.
The 0.66-liter econoboxes -- limited by law to lengths under 133.8 inches and widths less than 58.3 inches -- account for an amazing 40 percent of light-vehicle sales in Japan.
Kei cars, Japanese for "light" cars, were long the domain of Suzuki and Daihatsu. Now Honda wants to be a power player.
It has developed a new line of minicars from scratch and launched the first model, the N Box, last December. While the box-shaped tall wagon will be sold only in Japan, Honda is using it as a laboratory to perfect low-cost, small-car manufacturing techniques it can apply throughout its lineup.
"Everyone involved in the project hopes our technology is to be utilized in larger cars some day," Yasuaki Asaki, the N Box chief engineer, said in a recent interview. "Material costs will increase in the future as will the need for better mileage. So there is a need for more cabin space using less raw material."
 | Yasuaki Asaki squeezed space, fuel efficiency from minicar. |
Asaki, 54, pioneered several ways of squeezing more space and fuel efficiency from the minicar's restricted dimensions.
In Japan, minicars get special tax breaks for staying petite.
"Without technological innovation, you can't expand interior space because the outside dimensions are limited," Asaki said.
The most important innovation was dropping the usual monocoque body in favor of one that welds outer panels onto an inner frame.
That reduces weight and cost while improving rigidity. But it required Honda to develop new welding techniques that could reach nooks and crannies all but impossible to weld before.
It also required Honda to adopt a new technology called "tailored blanks" used to attach steel plates of different strengths and thickness. The goal is to meld lightweight, high-tensile steel to softer metal more suited to stamping.
It's tricky because the parts are hot-stamped and the cooling process needs to be precisely managed or the steel can fracture.
Honda tried this before with the Acura TL but failed. This time, Honda developed a cooling method that can be applied to mass production, paving the way to wider use.
"Through this process, the strength of the steel can be doubled and, in turn, the number of parts can be halved," Asaki says.
The new process allowed Honda to reduce the car's weight 10 percent compared with a vehicle built with a traditional unibody. That helps the car achieve better fuel efficiency.
Asaki was able to eke out additional cabin space by condensing the front collision zone by 7 centimeters (3 inches).
His engineers did that by reconfiguring the engine to collapse better during a crash. Its air compressor and alternating current generator swing into the powerplant on impact, while the intake manifold and catalyzer break apart.
That allows the car's frame to absorb more of the impact and the engine room to be more compact -- delivering more cabin room.
"In the long run, there will be a need for this kind of technology to use less material with more space," Asaki said. "This is a unique advancement in technology that was achieved because we had to work within the constraints of minicars."
Wheelbase: 2,520 mm (99 in.)
Width: 1,475 mm (58 in.)
Height: 1,770 mm (70 in.)
Weight: 940 kg (2,072 lbs.)
Seats: 4
Engine: 58 hp, 0.66-liter three-cylinder DOHC
Drivetrain: CVT, turbo and 4wd options
Fuel economy: 52 mpg, under Japan's testing mode
Standard features: Vehicle stability assist, driver and passenger side SRS airbags
Starting price: ¥1.24 million ($15,860)
Source: Honda
You can reach Hans Greimel at hgreimel@crain.com. -- Follow Hans on 
