This is a report about the introduction of the 2010 Prius in Detroit Michigan on Monday, January 12. Toyota invited 55 Prius customers and some of us extended our stay to attend "Industry Day" on Wednesday.

Prius 2010

I was fascinated by the engineering, cut-away model:

We see what appears to be a two-stage, catalytic converter with the second O_{2} sensor. The next assembly, "Exhaust Heat Recircuiation System" has two pipes, one colored pink and the other blue that goes to an over sized housing and some sort valve before the large resonator. The other ends of these two pipes goes:

The blue would be cool coolant and the pink the hot. We already know the Prius typically achieves catalytic converter operation within ~40-45 seconds. The heat from the converter feeds to the exhaust heat recovery unit and then feeds the engine block. What isn't clear is how the system handle the subsequent higher temperatures without stressing the coolant. Since the blue pipe appears to go into a cylinder with rod that may go to a valve, this may be how flow is handled.
CORRECTION: My thanks to David Beale who pointed this is the coolant heat exchanger that gathers heat from the exhaust. EGR remains an open question. I was able to confirm this by blowing up the original photos to read the labels.
I've not really studied exhaust gas recirculation (EGR) other than Julian Edgar's article. EGR helps reduce the combustion temperature and NOx emissions, which in turn allows a leaner mixture. If you look closely at the exhaust manifold, you'll see four pipes that feed into a central pipe and then a short pipe, probably the exhaust tap, that feeds to the left.

This photo shows the coolant pipes from the exhaust heat recovery system connected to the engine block. This eliminates the need for a thermos bottle and rapidly warms the engine.

The following photo shows how the larger inverter electronics now extends into the space formerly occupied by the transaxle, which is much smaller.

You can see the input manifold is plastic, similar to the Camry. Also, there still is a huge throttle plate. It looks like the cooled, exhaust gas passes from a pipe located just to the left of the top of the inverter. We can't easily tell where this feeds into the intake manifold. But you can really see the reduction of the transaxle.

The traction battery still has 28 modules identical to the current ones. However the housing is smaller. On the far right is a separate control electronics box and then a squirrel cage fan. With the control electronics as what appears to be a separate housing, battery replacement will be much easier.

OPINION: HSD does not require a significant amount of of electrical energy to keep the engine systems running at peak efficiency. The energy recirculation dance between MG1 and MG2 do all of the 'heavy lifting.' As such the higher energy density of the LiON is not really needed.

SPECULATION: Consider this, even with this marvelous traction battery, the vehicle _STILL_ uses an ordinary lead-acid, 12 VDC battery boat anchor. In a perfect world, the traction battery control electronics would provide the 12 VDC power and the lead-acid battery that would ordinarily be located about two feet behind the traction battery would disappear. This would save as much weight as a spare tire (or that space around my fat belly.)

There appears to be a bit more space for long legged individuals. However, I think we can wait on the official vehicle cabin specifications. I understand they've added 5 cu. ft. more space.

Here you see where for the show the auxiliary battery has been disconnected and a power supply provides the 12 VDC needed for the vehicle electronics. It sits on the right hand side just under 2 ft. (1/2 meter?) behind the traction battery control electronics. The tire well is huge and deep. The cover has about a 3-4 inch, ~10 cm padding. It might be just the right size for a bunch more battery modules as well as the space above the tire well.

The rear suspension uses a coil and shock absorber mounting. You can also see the muffler is well shielded by the rear axle and there is excellent heat shielding between it and the body. On the right appears to be a rear wheel 'mud flap' but in reality an aerodynamic shape to reduce drag (or trap winter snow and ice???)

The chief engineer, Akihiko Otsuka, who spent a long, long, day dealing with a lot of curious Prius fans who babbled at him in a foreign language, English. He was gracious, patient and totally overwhelmed by our insatiable curiosity.

Industry Day at the Detroit Auto Show

Ford Fusion

Ford has a Camry sized sedan powered by their unique, hybrid-electric system:

Mercury Mariner hybrid engine:

Dual Clutch - Why

Not one mention of energy savings even though computer shifted, 6-Speed, that does not used a torque converter should be more efficient than a torque converter based automatic.

Denso Electronics

Denso Electronics was one of only two, note worth parts manufactures at the auto show but they more than made up for all absentees. For example, this display shows their lane following, sign recognition and accident avoidance system:

They use a combination of radar and optical analysis to identify object, handle automatic cruise control, and driver safety assists. This is the wave of the future.

BYD Systems

This Chinese developed hybrid shares many of the basics but appears to be a little more massive than systems that have had many years and generations of development. But they have started on the path and this is reasonable first step.


They seem focused on just one aspect, optimum engine performance, with little or no regard for the whole vehicle systems. The variable turbine is important for adjusting the boost for different power regions.


It looks like they have a single, powerful motor and a massive battery. I don't know the operational principles.


The only tire manufacturer at the show, they emphasized their low rolling resistance. But sad to say, I've not found any engineering unit, no way to understand how much of an advantage they provide:


Notice the Mini-E has no back seat:

Double Clutch

The odd numbered gears are handled by one clutch and the even numbered gears by the other. This means before shifting, the target gear is aligned and the one clutch engage while the other disengages. This eliminates the 'shift' points as engine power is continually applied to the wheels:


The engine appears to have hydraulic lifters, the caps over the valves to reduce valve noise. However, the water pump belt remains whereas the Prius 2010 has an electric water pump.

This picture clearly shows the exhaust manifold with the four exhaust ports, the O_{2} sensor, and the fifth, exhaust gas port. The exhaust goes to the heat exchanger for the coolant and at the the top, front where there is an electronic control. You can also see the engine cover that helps to manage heat loss.

This photo shows the motor that manages the cooled exhaust gas and a pipe that feeds under the black control wire bundle/pipe to the intake manifold.

It makes sense that the engine controller operates this motor to feed the optimum exhaust gas ratio to the intake manifold.

This view of the engineering cut-away shows there is no belt because the compressor and the water pump are electric driven.

This is another view that shows in the lower right the belt-less engine and part of the electronic water pump and air conditioner compressor. At the lower part just behind the axel is the oil filter. The exhaust manifold and exhaust gas tap feeds over the coolant heat exhanger interface. The engine cover looks to be just a radiant shield.

The battery electronics housing is now separate from the battery housing. This should improve maintainability as well product improvement.

This VVT-i controller does not include the secondary cam follower that allows duration as well as phase angle change. The current variability changes the angle but does not change the duration so a throttle plate will still be required to manage the amount of the fuel air charge.


There was an engineering cut-out model of the two-mode.

This photo shows the first coupler has a pulse dampening spring. For the longest time, I thought this might be some sort of hydraulic coupling.

I am still disappointed that we don't have a good operational scenario and illustrated parts break-down. However, I am impressed by the relatively small size.

Because of the plastic sheets around this unit, good photograph was difficult. However, this shows how the front wheel drive, two-mode transfers power to the drive shaft area. This includes a six-speed, electronically switched transmission.

Saturn VUE Two-mode Test Drive
Not shown but a friend from GM took us on a drive in a Saturn VUE two-mode around the Bell Isle Grand Prix route. With three inches of snow, it was perfect for test driving a small SUV. Of course we tested the ABS with hard braking and the Saturn handled it perfectly. I never really heard the engine but as expected with all terrain tires, we heard the tire noise. A nice, five seat, SUV, the Saturn VUE two-mode is serious competition for the Ford Escape.