What Makes the New Prius Go?
By Bill Moore
Toyota estimates that 90% of current Prius owners will eventually trade-up to the next generation version of the world's most popular hybrid. What they will be acquiring is the fruit of a massive engineering and styling exercise that has occupied four and a half years time and the best efforts of 2000 engineers, led by Chief Engineer Akihiko Otsuka.
Over dinner at the Bardessono hotel and spa in Yountville, California, Otsukasan explained to me that when he was appointed chief engineer, his mandate was to improve the performance of the new Prius by 75 percent, a demanding goal considering the high standards the generation two model set when it first appeared in 2003.
I am fortunate in that I have been around this business long enough to have driven one of the very first generation one Priuses within twelve days when it went on sale on Japan in December, 1997. Toyota even provided me with a one of the early right-hand drive models shortly after they arrived in the United States.
I would get my first drive of the 2004 model at the Challenge Bibendum in Sonoma the fall of 2003. That 20 minute drive would be the longest time I would spend behind the wheel of the Prius until Toyota handed me the key fob of a red generation two model that I was to drive from San Francisco International Airport to Napa Valley, a roughly 90-minute drive. Enough has been written since that day about the Prius that there's not a lot I can add. It's a wonderful car and the some 700,000 that ply America's roads testify to its success with conscientious car buyers.
But Otsukasan was convinced there was room for improvement, but what wasn't going to change was the now hallmark Prius styling cues, what I originally referred to as its Clark Y airfoil profile. Aviation buffs will recall that the Clark Y airfoil kept the Lockheed Vega and Hawker Hurricane airborne.
As he managed the 100 team leaders who, themselves, managed their own teams of engineers, Toyota stylists set to work refining the design, which I was privileged to see at an undisclosed location in the fall of 2007. As a small group of us were ushered into the domed showroom and the drape was removed from the styling model, I think many of us were disappointed, though I not sure why. Maybe we were expecting the new Prius to be as different from the current model as it was from that little right-hand car I drove the fall and winter of 1999.
Still the new design was fresh while remaining distinctly Prius.
Overall, Mister Otsuka's Prius is nearly identical in exterior dimensions to the Gen II model. The wheelbase and height are the same. The body is half-an-inch longer and three-quarter inch wider. Toyota claims there is more interior space and since my driving partner for the day, Paul Gabe, is a strapping six-four and he seemed quite comfortable, I'll take them at their word.
The most apparent styling cue of the car are the squared edges at the front and rear of the car -- called aero corners -- as well as the sharp, pronounced shoulder line that runs the length of vehicle. It would be easy to assume all these were just fashion statements, an artistic nip and tuck that distinguishes this car from that. In fact, there are good aerodynamic reasons for these sharp edges, which are designed to direct the smooth flow of air over and around the car. Otsukasan's engineers even paid attention to how the air flowed under the vehicle, creating a Venturi effect and even adding a pair of guide vanes.
The emphasis on improved efficiency extends right down to the lights. The LEDs in the taillights consume 88% less energy than previous incandescent bulbs. LED headlights are also available that use 17% less energy.
While we're on the topic of efficiency, Toyota executives intimated to us that while you can get 17 inch tires on the Prius III, if you want the best fuel economy, stick with the 15 inchers.
Under the hood, there are big changes starting with the new, larger 1.8 liter engine. In fact, 90% of the trademark Synergy Hybrid Drive is new. The transaxle is lighter, the two electric motors known as MG1 and MG2 are new and improved, as is the smaller inverter. The new Prius eliminates the need for the thermos bottle system that preheats the catalyst to reduce emissions. It also reduces the time to heat cabin air by a full minute.
One of the complaints from early Prius owners in America was the missing EV-mode button on North American models. Available in Japan and Europe, the button allowed the Prius to operate in electric-only mode for brief periods of time as long as the battery had sufficient charge. The button is now there on this edition. In fact there are three driving mode buttons: EV, Eco and Power, as well as a standard default mode. The EV mode lets the car operate on electric power up to 25 mph. The Eco-mode provides more frugal throttle operation; the Power mode delivers more aggressive acceleration. As Toyota University's Chris Risdon explained it, eco-mode 'takes the lead out of a lead-footed driver."
Bring all the efforts of the designers and 100 teams together and you get a car the EPA rates at a combined 50 mpg, despite being 110 pounds heavier.
As he finished up his scripted presentation, Akihiko Otsuka issued his "Beat the Chief challenge to the assembled journalists. He had recently driven a 33-mile course that mixed city and highway driving around the Napa Valley and got 62.9 miles per gallon. He challenged the us to follow the same course and do better.
I did, but that's a story to be told after the March 25, 2009 embargo. In the meantime, for a dozen photos of the press preview and the cars we drove, click the 35mm slide icon below.
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