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Tuesday, May 1, 2007

Hybrid Field Research: The Toyota Prius


Hybrid Field Research: The Toyota Prius

By Rob Morrell, WORLDPAC Director of Technical Training


The Hybrid Hype
Whether it is celebrity approval, media coverage, personal recommendations or just plain-old curiosity, hybrid vehicles are gaining speed . . . literally.

When I began researching hybrids, I asked a variety of people what they thought about the vehicles and the ideas behind them. I must admit, I have never heard so many extreme views on any other car as I have the Toyota Prius. A love or hate relationship seems to exist with the Prius, and every person I spoke to had an opinion about it. I asked dealership technicians, instructors and even some top people at Toyota. Some laughed at me for even asking, but what really surprised me is how strong the opinions were from intellectual industry professionals who had never even driven a hybrid. The more I learned about the Toyota Prius, the more interested I became, so much so that I bought a 2007 when they came out with the Touring option.

Hybrid Theories: Honda & Toyota
There are two basic hybrid vehicle theories at work: the Honda’s and the Toyota’s. The Honda approach is to build the car as lean as possible; build the most sophisticated and economical engine for it and use electric motor and battery systems to supplement the already well designed engine based power system. Toyota, on the other hand is pretty heavy and uses mostly steel instead of aluminum, uses basically an off-the-shelf engine from the Echo and uses a motor and battery system like the Honda, however, with a much more sophisticated and substantial electrical system. In summary, Honda mainly modifies the engine; Toyota modifies the electronics and CVT transmission.

Technology
Toyota Prius technology . . . Where do I begin? The later and more current Prius models are much improved over the original model (as most recent models are). A 1.5 liter 16 valve engine with variable valve timing and a 13.0:1 compression ratio produces a mind bending 76 horsepower at 5000 rpm and a neck snapping 82 lb-ft of torque. Add to this an improved and more powerful electric motor that can spin up to 67 horsepower and 295 lb-ft of torque. Sum them up and you have almost as much power as a normal car. But, before you get to excited you have to take into account the extra motor and battery weight, making this little machine tip the scales at about 2932 pounds, so it’s not as fast as you might think. The batteries and inverter are also very sophisticated. There are 28 – 6.5 ah batteries in the back and an inverter set up to handle as much as 500 volts! In this sense, the Prius has the technological edge over Honda.

The Prius is almost completely computer driven. The engine/motor setup is extremely computer controlled; the steering, the brakes and so on. All this feels a bit awkward at first, as almost everything you do (control wise) is driven by a computer that interprets what it is you really want it to do. For example; if you turn the wheel left the car turns left, if you step on the brakes it slows down, and if you step on the gas it speeds up. As a result, when you drive a Prius for the first time all the computer generated commands can make it feel like the car is smarter than you.

The engine is nothing overtly special by today’s standards except that it is incredibly clean at the tailpipe. In fact, the Prius is one of the cleanest cars ever produced. In addition to a unique battery, the Prius engine also has a normal battery and starter, although they are rarely ever used. The transmission is very special; it is a CVT, which is common these days, but not your typical CVT because it has no belt! Alternatively, it uses planetary gears to manipulate the RPM’s, kind of like an exotic automatic but with infinitely variable ratio’s within it’s operating range and very compact.

The brakes look like normal discs up front and drums in the rear but they are electronically controlled and rarely used, so they usually last 150,000 to 250,000 miles due to the fact that the electric generator/motor does most of the braking. Also, there is no hydraulic connection between the pedal and the braking system, as the pedal is electronic. The steering mechanism is connected to the front wheels but is entirely electronically assisted so it works whether the engine is running or not (this is a good thing because the engine seems to only run when it wants to). The AC is also electric so it works with the engine running or not and the heater is supplemented by a hot coolant tank that keeps the engine coolant hot for up to three days.

What little is left is pretty much like a normal car. The Prius has a spare in the trunk, regular tires, shocks and springs, and so on. It has a full house of airbags and stability control/ABS and my model has NAV, a back-up camera, voice recognition, keyless entry/start, and of course Bluetooth. The back-up camera is awesome. The voice recognition works decently, but not perfectly. The Bluetooth will work with several phones and address books, but is a bit of a pain to sync with a phone. With voice recognition, NAV and a Bluetooth phone you can have a couple conversations going on at the same time, but for the most part, the car manages to keep it all straight.

Test Drive
At first drive, the Toyota Prius is a humbling experience. You need only the key in your pocket and the car senses its whereabouts at all times, inside or out. Grab the door handle and it unlocks and opens at the same time. Get in and hit the start button (again, it recognizes the key is in your pocket) and with your foot on the brake pedal and the ignition set to “on”, put the transmission lever in “D” and take your foot off the brake to depress the gas pedal. At first, the car will probably start moving in ‘stealth mode’ without even starting the engine. When you reach enough speed or you push harder on the throttle, it will start the engine and seamlessly add engine torque to the motors. More gas equals more engine RPM and power; less gas equals less RPM or it may all-together shut the engine off depending on what it decides to do to meet your request. The brakes and steering have almost no feel whatsoever, so it takes a couple of days to acclimate to everything that is going on through the seat of your pants. After a few days it becomes second nature and you just get in and go like any other car.

Performance
In my opinion, the first Prius models were pathetic. With only a 6.5 horsepower outboard, it was like driving a small boat in a big ocean. In 2004 Toyota made drastic improvements, but to be fair, each year they have made a few nice improvements. For 2007 they finally offered the sport or “Touring” option, and without this package I could not have been convinced to buy one. The Touring package is essentially just European suspension, but what a difference a few adjustments can make! Bigger 16” wheels replace the usual 15”, bigger sway bars, and stiffer springs and shocks make this a reasonable car to drive. It is not going to push any 911’s around but at least I can go around 45mph turns at 65mph without too much excitement. It feels more neutral than a normal Prius, but, then again, a normal Prius understeers like a plow in soft soil. For an extra $800 the Touring package is the only way to go. TRD also makes several pieces for the car including a whole array of chassis braces as well as a spring and shock kit. The story goes like this, “I am not trying to go fast, just not slow down so much for the corners in order to save more fuel and thus the environment. You see, I am putting on the suspension kit on for the frogs, birds, ozone and everything else . . . It’s a completely unselfish thing to do!”

Service
I spoke with a good friend of mine, a shop owner in California, about the service needs of a Prius. He stated there was nothing on the Prius to service. This is not exactly true. The Prius needs oil changes like every other car. In my Prius, I use Synthetic oil and replace it more frequently than Toyota recommends. The Prius also requires services on its’ two cooling systems, its’ electronic A/C system, its’ transmission, batteries and so on. It is imperative that you are familiar with these cars before starting your service due to the high energy output. Remember, on hybrids both the voltage and amperage are much higher than anything you have at home, so this means no second chances. All things considered, it is really no big deal to work on once you learn where everything is and how it operates.

My Experience
Having driven this car for about 7,500 miles now, I have become accustom to its ways and it has taught me how to achieve better and better gas mileage. My worst gas mileage has been 42.5mpg and that was going 75-85mph to work and back as I would normally drive my BMW. If you keep it at 70-75mph you get about 46mpg, and it will do even better if you keep it under 70, but I personally lack the willpower to do that for any length of time. In stop and go traffic it’s KING! In this case, it gets about 55-60mpg and the engine hardly ever runs so it is dead quiet. Zero-to-60 is about 11 seconds and it tops out at about 104-105mph electronically. The brakes on this front wheel drive have no issues and the handling is fine, especially considering how big this car is on the inside. It has secret compartments all over the place and like most Toyota’s, a bunch of cup holders (an impressive 10 in total). A $25 fill up will drive you for about 450 miles, and in my experience, a full tank will run for approximately 550 miles. I like these features and the fact that it’s so easy to drive in stop and go traffic, I’m quite pleased I bought it. Does this replace my desire to drive Porsches or BMW’s . . . No, but overall I enjoy the car for what it is.

Looking Ahead
In terms of new concept cars, the latest hype is about the German diesel cars that are coming soon, but living in Silicon Valley, everyone is always looking for the next best thing. I waited for Toyota to refine the hybrid and I am happy with it so far. It functions properly and everything it does is intriguing. Who knows, maybe a diesel hybrid is next. In the end, I cannot verify the car is truly better for the environment, but I feel that with all this technology it is a step in the right direction. I do not yet know how well it will hold up but I am willing to give it a go and see how it turns out. It may not be for everyone, but it is perfect for my 120 mile per day commute in heavy traffic, and it is definitely an advance in technology. Here in Northern California, it is a very common car to see on the road. Now, if only hybrid service shops were as common as hybrid drivers, business would be booming and hybrid owners would be smiling alongside the frogs and birds.

In the very near future we will see a number of new vehicles on the road that may not be called hybrids but use the regenerative braking, warm start technology, carbon intake filters and the CVT transmission; this technology is here to stay. I no longer see the Prius and other hybrids as unique vehicles but rather a starting point as we incorporate all of these systems into regular everyday cars, even performance cars. With more systems that require service and repair I think the future is bright for the repair industry.


Rob Morrell is WORLDPAC’s Director of Technical Training. To learn more about WORLDPAC’s Technical Training program and the WORLDPAC Training Institute (WTI), click here.

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