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Toyota iQ



Lightweight and well packaged, Toyota's iQ is set to make a big impact in the city car segment.

By Simon Bickerstaffe

Europe is good at small cars but Toyota’s iQ is about to crash the party. It will tap into the growing A-segment. Increases in urban congestion, fuel prices and CO2-led taxation will make city cars more and more popular. Sales of cars emitting less than 120g/km CO2 netted 10 per cent of the EU’s total market.

The iQ is anything but conventional, not least because of its layout. “Kei” class microcars aside, Japan prefers large cars so Toyota had to learn from Europe, while coming up with something special. “We changed the way compact vehicles are made,” says chief engineer Hiroki Nakajima. “But we learned from Europe.”

The iQ doesn’t share architectures with other Toyotas. Mass reduction was the five-year programme’s main aim, occupying Nakajima’s team for the first three years.

Toyota engineers don’t stay on one product group. For many, including Nakajima, this was a new challenge. ”My previous project was the RX400 SUV,” he says. “The iQ weighs 845kg-955kg. We optimised the mass of every component.”

The iQ is 2.99m long, with a 2m wheelbase; the Aygo measures 3.41m by 2.34m. Unlike Daimler’s Smart and VW’s Up, the engine is in the front but frontal impact performance isn’t compromised. The body has an extra B-pillar reinforcement to absorb crash energy and new side airbags. Toyota expects to get five NCAP stars.

Toyota rethought the interior packaging. “I’m very tall, so’s my wife and my father – the three of us like to go shopping so this was the concept behind the iQ,” Nakajima says. “We wanted to increase cabin space so chose the 3+1 arrangement.”

The front passenger seat slides forward to let a third adult sit in the back. The area behind the driver is big enough only for luggage or a child. The seats are slim, one-piece mouldings that weigh 30 per cent less than a standard design.

Toyota scooped 40mm out of the seatbacks, creating knee room in the rear, but making it difficult to maintain whiplash performance. The frames were reinforced with high-tensile steel to compensate.

The HVAC system shrunk by almost a third – a higher performance blower moved to the top, reducing overall height. This let the unit move closer to the windscreen’s base, freeing up more cabin space.

“The airflow route changed and it’s difficult to use such a small space,” says Nakajima. “So we altered the airflow turbulence so as not to affect performance.” Toyota could apply the technology to other vehicles.



The drivetrain contributes to the iQ’s compactness: “By repackaging the differential, we could move the front wheels forward,” he says. The iQ will have automated manual (AMT) and continuously variable (CVT) transmissions. CVTs are popular in Japan but haven’t caught on here. Nakajima says their smoothness improves driving performance, important in premium products.

The car emits as little as 99g/km CO2. Toyota will offer two gasoline and one diesel engine, but won’t give details yet. Toyota has a stake in Yamaha but Nakajima says the firm isn’t involved. The Aygo’s all-aluminium units would be ideal – the 1-litre three-cylinder gasoline unit weighs 67kg and delivers 50kW (67hp) and 93Nm.

A stop/start system and electrically assisted power steering help fuel efficiency and emissions. “We have no plans for a hybrid version,” says Nakajima. Fitting in the battery would be hard and add too much weight.

Toyota wanted high agility at low speed and stability at high speed. The firm increased kingpin offsets and lowered the centre of gravity. The suspension was developed to limit understeer and has a lightweight rear torsion beam; multi-link is too costly and heavy.

A short wheelbase can lead to instability under braking; electronic brakeforce distribution controls the yaw rate when stopping from high speeds.

Production starts in late 2008 in Takaoka, Japan alongside the Corolla and the Yaris. The firm expects to reach 100,000 units in the first 12 months. Toyota expects to sell half a million small cars in Europe by 2009, including the Yaris and Aygo, which together sold 370,000 units in 2007.

That doesn’t seem too ambitious. More buyers want comfort and refinement in a smaller, more efficient package. The iQ should be popular.