Toyota shows off its new iQ electric-car prototype

Toyota shows off its new iQ electric-car prototype
(PhysOrg.com) -- The Toyota Motor Corporation is set to show off its EV car, an electric-car prototype version of Toyota's iQ model, at the Geneva auto show next month.

The EV prototype car will have an electric powertrain that is based on the current Toyota Hybrid Synergy Drive system. This system will feature a flat lithium-ion battery pack which, according to Toyota, will be able to give the car a driving range of up to 105 kilometers, or about 65 miles, on a single charge. Obviously, the car is built for short-range transportation, and not for use on longer trips, which is a common issue with .

This is a preview only, since sales of the car will not begin until an as-yet-unspecified date in the year 2012. At first, the EV is likely to be available in Europe through a leasing plan, once it finishes its road testing, which will also be done in Europe. The car will also be available in North America, and some other markets which are currently being investigated for their viability.

  • Toyota shows off its new iQ electric-car prototype
  • Toyota shows off its new iQ electric-car prototype
The car is slated to fit three passengers, which makes it smaller than both the Mitsubishi i-MiEV and the Nissan Leaf, two currently popular . This is, of course, not Toyota's only attempt to make an electric vehicle. They are also working with Tesla Motors Inc. to create an electric version of the RAV4 compact SUV which is also planned to be released in 2012. Several other vehicles are in the works for the future, but they have much longer wait times, such as the sedan-type fuel-cell expected to launch in 2015 in Japan, the U.S. and Europe.

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Feb 15, 2011
Why not make the chassis the battery? That would save alot of weight. Also why is there no direct wheel motors on the wheels ?

Feb 15, 2011
A fair assumption for everyday road cars would be .3 kWh per mile based on driving reports from the other electric cars.

Feb 15, 2011
Why not make the chassis the battery? That would save alot of weight. Also why is there no direct wheel motors on the wheels ?


Because wheel motors are difficult to optimize for high/low speeds and difficult for the suspension system. They're basically too inefficient as a compromize.

Feb 15, 2011
Because wheel motors are difficult to optimize for high/low speeds and difficult for the suspension system. They're basically too inefficient as a compromize.

nonsense... with direct wheel motors you can reduce alot of weight, and with sensors you can easily regulate the speed of the wheels. Also taking corners would be more efficient cause the car can make one side spin faster than the other.

Feb 15, 2011

nonsense... with direct wheel motors you can reduce alot of weight


Despite that, a lot more weight will be unsprung, which hurts handling and ride quality a lot. When a heavier wheel bounces from a pothole, the motion carries a lot more energy that has to be damped by the suspension. It jostles the car around much harder. And the heavy batteries will void the weight advantage anyways.

And every car these days has a differential, making one side spin faster than the other in corners.

Feb 15, 2011
Besides, much more weight is saved with high-speed electric motors, because they have a much better power-to-weight ratio than low-speed wheel motors, and they're more efficient overall.

Feb 15, 2011
Despite that, a lot more weight will be unsprung, which hurts handling and ride quality a lot.


Not exactly what you mean but if you are talking about suspension that is simply not true, it jsut requires different techniques.

When a heavier wheel bounces from a pothole, the motion carries a lot more energy that has to be damped by the suspension. It jostles the car around much harder.

True, but cars are meant to drive mainly on the road. Also a decent suspension doesnt have this problem at all especially when there is no axis it effects the car less and just the local suspension, thus more energy efficient.

And the heavy batteries will void the weight advantage anyways.

Direct wheel motors or axis motor, the battery weight or position doesnt change.

And every car these days has a differential, making one side spin faster than the other in corners.

Thus losing efficiency in the differential.

Feb 15, 2011
Besides, much more weight is saved with high-speed electric motors, because they have a much better power-to-weight ratio than low-speed wheel motors, and they're more efficient overall.


I dont know the exact numbers to say anything about that but it would be an interesting battle to test this out in practise.

Feb 15, 2011
If you think unsprung weight doesn't matter to ride quality, especially in a small vehicle, you're not worth talking to.

Feb 16, 2011
iQ? better get in line...

hope they find a better name for the european market

Feb 16, 2011

Thus losing efficiency in the differential.


Less than 3%, depending on the differential. Much more is lost in having to use higher currents to produce power in a wheel motor.

The problem of electric motors is that their efficiency drops dramatically at speeds below about 20% of the nominal speed because of the high currents required to make power. That means, if you "gear" a wheel motor to go 100 mph, it will be really inefficient below 20 mph, and they struggle to produce power without overheating.

High speed motors aren't trying to produce much torque because the gears turn the speed into torque. That means the required magnetic field strenght is lower, less current is needed to produce it, the mass of the copper in the coils is smaller (fewer turns of wire), and the resistance is reduced, all leading to higher efficiency. High speed motors can also be run "overspeed" much higher than low speed motors because of the smaller inductance of the magnetics.

Feb 16, 2011
To really appreciate how much wheel hub motors weigh, you can take something like Ford's Hi-Pa Drive HPD30 which weighs 18 kilograms and produces 40 kW peak and 2000 rpm. (1:2 ratio between sustained/peak is typical unless extra cooling is provided)

High speed motors like CPM RFTR can do 50 kW (100 kW peak) and 6000 rpm with a weight of 14 kg, and with an efficiency of over 96% according to the manufacturer.

Adding 18 kilos to a wheel almost triples the moving weight that has to be damped by the suspension, which has a significant effect on the ride quality. It also puts more stress on the brakes because of the energy stored in the rotation of the heavy wheel.


Feb 16, 2011
I had a funny thought about the range. Any normal cars fuel guage would be in or almost in the red with only 60 miles fuel left in the tank.

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