Free Fuel Incentives Hop Across the Atlantic
Toyota Chairman: Japanese Automakers Trying To Meet EU Carbon Standards

Toyota to Enter GS450h in 24-Hour Endurance Race

Toyota will compete in Japan’s only 24-hour semi-international racing event with a modified Lexus GS450h hybrid sedan. (Earlier post.)

The Tokachi 24-hour Race will run at the Tokachi International Speedway in Hokkaido (in northern Japan) from July 15 to 17. By entering a Lexus GS450h, engineers, with an eye toward obtaining technological feedback for future mass-production vehicles, position the race as part of their ongoing developmental efforts, hoping it will provide insight into how to make hybrid systems smaller, lighter and more efficient. They also plan to collect data on the potential of hybrid systems in motorsports.

This marks the first time an automobile manufacturer has played a leading role in entering a hybrid vehicle in a competition that has semi-international status, such as the Tokachi 24-hour Race. Until now, in Japan, only private teams with self-owned hybrid vehicles have competed in independent events at various racing circuits.

The car, the Denso Lexus GS450h, is entering in the “Production-1” Class (hybrids and other environmentally considerate vehicles). The entry vehicle is also recognized as a 2006 Super Taikyu Series ST-1 Class (3,501cc or higher) vehicle exceptionally approved by the Super Taikyu Organization (STO).

Main modifications on the car include:

  • Front and rear suspensions
  • Tires and wheels
  • Safety roll cage
  • Safety fuel tank
  • Differential (mechanical LSD)
  • Brake system
  • Aerodynamic parts, reduced vehicle weight, etc


Rafael Seidl

Racing is all about power and fuel economy. If the vehicle only needs to last one race, they could push the envelope on the electric motor during braking and acceleration, especially if they rip out the battery and replace it with a set of ultracaps (and the control logic mods that implies). The rules for this race probably give them a lot less leeway on engine modifications.

allen Z

Here here.'!
Rally racing may make use of it too, as would Le Mans. Nascar has a truck racing series that may take the equiptment in the bed. Then there is tractor racing. Suped up 18 wheeler tractors without the trailers:

Roger Pham

Correct me if I'm wrong, but I believe that high-end high-performance luxury cars have come a long way in term of safety, power, handling, and durability, such that there could be racing events that requires 100% stock cars massed produced with at least 3,000 copies yearly, without any major modification allowed, with exception of course in deactivation of the speed limiter to allow the vehicle to speed up to its drag limit, and removal of non-essential luxury items, such as power seats, power windows, stereo, AC, etc. Many high-end cars now have variable shock rate suspension, variable ride height, and they are constructed a lot more durable than cheaper models. They have front and side airbags as well. Many have 400-500 hp engine on relatively light chassis once all non-essential luxury items removed, almost equal in hp/wt ratio of the NASCAR, which cannot weighs less than 3500 lbs (at one time, don't know if it's still true). I believe people who pay >100,000 USD for such luxury cars ought to have a chance to find out how their car would hold up in a race. There should be different classes of races for cars of different sticker prices, for example, $100,000 car should not compete with $300,000 exotics, and sedan not against 2-seat coupe. Furthermore, cars should have major components built to last for the entire racing season, and not having engines and suspension rebuilt after each race, with exception of the tires, which are cheap and should be replaced at least once for each race.

There is no more effective way to spur innovation and safety than racing and market competition. Racing is definitely a lot more fun than the latter.

shaun mann

this is mostly just going to be a test of their petrol engine. the electrics will only play a minor role and probably a negative one. it will certainly be good advertising fodder, though. "world's fastest hybrid"

a hybrid system only charges the batteries when the vehicle is cruising or braking. during a race, this means only when braking. even with ideal batteries (or caps or whatever), ideal electronics, and ideal 100% efficient motors, the car can only capture as much energy as the electric motor's power * the time spent braking.

the driver then accelerates at full power out of the corner. with the ideal system described above, this means the energy stored while braking will last exactly as long as the braking did. so, 2 seconds of braking will store enough energy for 2 seconds of accelerating, which doesn't amount to a whole hill of beans during a race. in real life, using non-ideal components, you'll probably find that it takes more like 10-15 seconds of braking to store enough energy for 2 seconds of acceleration.

what does amount to a whole hill of beans during a race is the extra weight of batteries, a mostly unused electric motor, and electronics. this car would be significantly faster without the hybrid bits.

so, not exactly a good engineering or racing practice, but they'll probably mention it in every ad for the first year of sales.

Roger Pham

Shaun mann,
It so happens that the Hybrid Synergy Drive (HSD) is arranged so that during regenerative braking, both the traction motor(s) and the starter/generator can capture regenerative energy. During braking, the engine is slowed down,and in so doing, will send the starter/generator spinning real fast, thus will turn it into a very powerful generator due to its high speed. So, a lot more energy can be captured by both the traction motor(s) and starter/generator than you think. If the battery is not up to snuff in storing all these electrical energy, then an Ultracap can be added to capture the rest of the energy. When comes time for acceleration, all hell will break loose with oodles of torque coming out of all wheels, because I believe that the GS450h has traction motors on both axles, thus better road grip without wheel spinning. A NASCAR racer only powers two rear wheels, so the amount of torque tolerable by the rear wheels is much more limited, or you'll have wheelspin. An electric motor has maximum torque at zero rpm, so you'll have a lot of starting torque in all 4 wheels, and after the car starts to accelerate, the power will "keep on coming", courtesy of the super-duper engine with DOHC-4valve/cyclinder and vvt-i, AND the battery and ultracap dumping all the watts and volts into the traction motors.

All the extra motors, battery and ultracap behave like another engine to the car, allowing the engine to be downsized and hence saving engine weight and fuel burn, AND the electric drive components ALSO act as a 4-WHEEL DRIVE TRANSMISSION for oodle of torque to all 4 wheels without additional weight and friction of a mechanical transmission and a 4-WD unit.

But U have a great point, depending on the type of race. If it is an oval racing circuit with little recuperative braking like Indy 500 or Daytona 500, then, yeah, hybrid may not be too advantageous, depending on the aerodynamic merit of the car. Cars with great aerodynamic drag saving will require less power during flat-out cruise, allowing the engine to recharge the battery and ultracap after acceleration in the straight away, and to return the favor, the battery and ultracap will dump all their volts into the motors during the acceleration after the banking turn. And then, if the racing circuit is like F1 in layout, with a lot of braking and acceleration, then, hybrid would be hard to beat due to a lot of time saved from fueling pitstops.


Let's wait and see, but if hybrids start winning races..........


Let's wait and see, but if hybrids start winning races..........


please take a look at the circuit :

As you can see there are HUGE potential regenerative braking opertunities. I completly agree with Roger : the HSD Hybrid allows for a smaller more efficient engine, and the permanent 4 wheel drive gives you a real edge.

I know this 'cause i regularly test my Prius in traffic light situations, and having no gear, i almost allways win, no matter how beefy the competition :-)

shaun mann


The motor arrangment doesn't matter. I assumed it, along with the transmission system and most everything else was ideal to demonstrate the energy problem in racing.

See, in a road race, the car is accelerating full power when going straight, decelerating full power when entering a corner, and for very short periods of time it is only partially accelerating during a corner.

For the hybrid components to be useful, they have to have energy stored. Energy can only be stored while the vehicle is braking or while partially accelerating in corners. During these times, the most energy that can possibly be stored is equal to the electric motors' rating multiplied by the time.

This stored energy is then used to accelerate the car. The car can only use as much energy as has been stored during the braking and partial acceleration times. So, for a given lap, you add up all of the time spent braking or under partial acceleration and that is the amount of time when energy was stored.

In our imaginary ideal system with 100% capture and storage and perfectly efficient acceleration, you can accelerate for exactly as much time as the total of the time spent braking and under partial acceleration. So, if you are braking or in corners for 10 seconds each lap, you will have hybrid boost available for 10 seconds each lap.

In the real system, batteries cannot ever exceed 50% efficiency. Under the heavy charging and discharging circumstances you'll find in a race along with elevated battery temperatures, it is very unlikely that the hybrid bits will exceed 30% efficiency.

We can use this percentage as coefficient to our energy storage time. So, if you spend a total of 10 seconds braking and cornering during a lap, you will have 3 seconds of full hybrid boost available.

So, if we look at the course, a few test laps could tell us how much time will be spent braking and cornering. we can multiply that by our .3 efficiency factor and we'll have the amount of time we can use the full hybrid boost. During this amount of time, the hybrid components help the car accelerate.

We can then add up the rest of the time that the car accelerates. During all of this time, the hybrid components are dead weight, contributing exactly as much to the winning of the race as the radio and air conditioner.

Considering that the GS450h is slower to 60 than the GS430 despite having more power, we can assume that we are not talking about an insignificant dead weight.


"For the hybrid components to be useful, they have to have energy stored. Energy can only be stored while the vehicle is braking or while partially accelerating in corners. During these times, the most energy that can possibly be stored is equal to the electric motors' rating multiplied by the time"

Wrong: Toyota's HSD system wil go to extremes to keep the batteries in healthy operating conditions. The "gear" will allways devert energy to the "starter motor" to load the batteries, even if it means that the car will not accelerate as fast as it could if the batteries were ignored and all power were to be directed to the wheels.

So you have to look at the engine + motor + battery as one system, and you will see it saving loads of fuel, and giving it tons of extra torque, to get away quickly.

We'll have to wait and see, but i think one might be surprised.......

Roger Pham

shaun mann,
I agree with you that the battery is the weakest link in the hybrid arrangement, especially with high amperage charging and discharging for a 24-hr race. That's why I've stated that if the battery is not up to snuff, then add the ultracap for more efficient and rapid braking recuperation. I don't know if the racing rule would permit that, but, since racing can be considered as a real life laboratory for technology development and validation, then a racing governing body with good foresight should permit the addition of ultracap for more effective energy storage.
Modification for a hybrid race car should provide much more cooling to the battery, as well as enhanced cooling to the stock engine in order to take away the extra heat.
I suspect that with adequate provision for battery cooling, the battery efficiency will be better than the 30% figure that you've provided. Under optimum charging, battery efficiency can be as high as 90%. Toyota's hybrid battery is designed with extra large plate contacts with emphasis for maximum power possible over capacity, thus inherently low internal resistance. A NiMh battery can take a very fast charge without significant heating up, not until the charging at near full capacity that the battery will heat up and become inefficient. Between 30-70% of charged status, NiMh can be charged and discharged very efficiently, with ~90% efficiency. With very high amperage in racing condition, efficiency may drop down to 60-70%, but surely not below 50%. Factoring in losses in the motors and generators, and total regenerating efficiency may be ~50%.

Most of the hybrid components are not dead weight, because they constitute the transmission unit, replacing a mechanical gear set. Hybrid components are heavier, largely due the battery, but the gain in fuel efficiency thus less wasted time spent in the pitstop, will probably more than making up for the slight slow down due to heavier hybrid components. Replacing the battery with ultracap with a lot less weight will improve the hybrid weight disadvantage. Downsizing the engine a little bit will further reduce the weight disadvantage of hybrids. The Prius at 2900 lbs is not heavier than a non-hybrid car of comparable internal dimensions and performance. The Camry hybrid weighs no more than the Camry V6 and having performance quite comparable to the V6.

Let's just wait to see what'll happen, who will win, eh?

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)