Toyota Prius Hybrid - Experiance from a user, Part 2

Part 1 of this was something I just casually wrote in the hope of it will be of some use for few. Turns out there were lot of readers than I anticipated! May be it will not be a bad idea to share some of more detailed stuff too... Things I didn't put in the first post since I wasn't sure about the level of interest on technical details of a  Prius.

Tires : My model came with the most uncommon type of 165/65/15 low resistance. This was the type recommended for 1997 model Prius. Since fuel consumption statistics, mileage meter all must be depending on the tire radius size, all the statistics the car indicates to us could go wrong if we change the tire radius. However, using a different tire radius is not possible without changing Rims so I guess this is not a common scenario. However, tire inflation level is! Fuel consumption difference between using properly inflated tires and poorly inflated ones can be noticeable! When the tire is deflated, the length it covers per a single rotation is less, hence more rotations will be needed to cover a unit distance, resulting in high fuel consumption.

Surprisingly, 1997 model recommended tire pressures to be at a staggering 42 psi. Normally in Sri Lankan roads we use a pressure level of 28-32, most people preferring 30. in 1997 Prius, front wheels needed to be pressurized at 44 while the lower once were expected to be at 42. Difference was to offset the additional weight of the front area. Now, I infact tried those! want to know what happened ? Well, I got amazing fuel economy for a while and then I had to replace shock absorbers! Understandably, I haven't tried it since then. This setting is certainly not for non carpeted roads of Sri Lanka. Then again, we have much better roads now compared to 5 years earlier and if you are one of those lucky ones who can use a carpeted road all the time, then you should definitely give this a try. Inflating tires is a well known strategy to conserve fuel, something which was even suggested to all Americans by Obama himself!

Breaking : Because of the electric breaking in Prius, it is expected that one do not need to replace break pads that often. Can some one give us some statistics on this for a normal car? in my usage of the car for 6 years (close to 100,000 km)  I had to replace break pads just once. Like mentioned in the previous post, most of Prius parts are compatible with other Toyota models, and Toyota parts are not so expensive either so this was not something to boast about really. On the other hand, regenerative breaking is saving much more in fuel than saving on break pads. Statistics say that if you use it properly regenerative breaking can save up to 17% of the kinetic energy which will otherwise go totally wasted. Here, 'properly' means that to get the full benefit of regenerative breaking, we need to apply breaking smoothly. A gradual slow down of the car over a distance where we can clearly hear the humming noise of breaking. A sudden break will not be turning much of kinetic energy into electrical energy. (but it will save lives in an emergency! so do apply breaks with full force when you have to...)

Fuel economy hints :
This fact has been mentioned before but let me go through it again as this is the single most, biggest reason behind fuel wastage, even on a hybrid!

Trying to speed up (accelerate) when that is not really needed or meaningful.

How many times we see someone overtaking us, but then we catching up to them after driving normally while they are waiting at a color light! That is insane driving, we get no benefit at all by accelerating and be the first to reach a particular color light! If we know there is a stop in front, best and most sensible thing to do would be to stop accelerating and allow the vehicle to slow down, we could time this to perfection so that the vehicle stops at the exact spot is should be stopping. Doing that is much fun too! On highway, the strategy should be to drive in a comfortable constant speed (around 30-70) by tapping the accelerator lightly. Display should tell us when we are doing well in fuel economy. (instance bar hovering around 30 km/l) It is those occasions that we should try to lengthen. All these help us concentrate more on our driving and speed, which make us good safe drivers. Some of US states have actually reduced insurance amounts for Prius noting that Prius drivers get involved in far less amounts of accidents than the others. I guess this applies to other hybrid drivers as well. Being sensitive to fuel economy and be attentive to driving both go hand in hand.

As mentioned in the last post, a one cool feature of Prius is that the engine can automatically stop when the vehicle is idle (like waiting in traffic). This saves lot of fuel in city driving. However, this also means that the engine get auto started when we eventually start to move. (initially the vehicle goes solely on battery and then switch into petrol) When the engine get stops and started again frequently like this, it will put up a higher burden on the normal 12V car battery. If the Prius has to perform well, this 12V battery also need to be in good shape. Needless to say, power steering also is on electric so the stress on this battery is really high. This is one lesson I learnt after going through some hassle. It is natural to pay more attention to the bigger costly battery and forget about the little one. So make sure you keep a good eye on the little 12V fella as well!

One caveat in auto stop and start of the engine is that it works as expected mostly only when the AC is not running! reason ? In older models of the Prius (such as my one), AC gets the power from petrol engine like in any other normal car, so if the AC has to work, you need the engine running. In this case, sometimes even if your vehicle is idle, petrol engine will keep running. Turning AC off when the car is at a stop is not always possible in hot days. However, in recent models (after 2003 I guess) Toyota has improves on this by making AC also to run on battery! So the owners of newer models... let us know whether petrol engine totally stops at  traffic (while AC is fully on)

Looking at the fuel efficiency more on the LCD display is a great way of adjusting our driving. In a display like the image above, rightmost bar is our instance performance that is how many km/l or miles/gallon are we doing RIGHT NOW. Other 6 bars are average fuel consumption in last 30 minutes divided into 5 minute periods. One thing you will see most of the time is that the average efficiency in the first 5 minutes of the journey is usually low. Reason for this is that the petrol engine (of any vehicle) needs to get heated up to a optimal temperature to perform well. Until it reaches that point it can't maximum efficiency. This means if the usual drive is about 20-25 minutes or shorter, then the overall fuel efficiency suffers noticeably due to the first 5 minute issue. In later models Toyota engineers have come up with an ingenious solution to improve on this. They have introduced a vacuum flask which will keep all the heated air when the engine stops and use that when the engine get started next time. This reduces the need to heat the engine all the time. Just a one example how far designers have gone to provide the maximum mileage for each drop of fuel..  

What about things which can go wrong... (As Murphy's laws predict, "If something can go wrong, it will - at the most inappropriate moment") I have some experiences to share on these issues as well. Will try to share them with you in another post. Meanwhile, feel free to send in any questions and your own experiences, those will be most welcome!

Happy, Safe, Clean and Economical Driving!

Toyota Prius Hybrid car - Experiance from a long term user

 (http://upload.wikimedia.org/wikipedia/commons/7/7a/TOYOTA_Prius.jpg)

When the government reduced import tax for hybrids and people started to buy Prius cars, I started to get so many calls from friends and from friends of friends. For few weeks, it was as if I was a Prius dealer, expert or a mechanic! Well, I'm non of above yet I helped those callers to the best of my ability. It is then it occurred to me that if I put a blog post, it would be useful for some people and easier for me as well! The recent post by සඳරු at හිස් අහස prompted me to put that thought into quick action...

Now, the reason why people asking me about Prius issues are because I'm one of those rare guys in Colombo who was (put your favorite adjective in here. crazy/stupid/brave/lucky whatever) enough to buy an earlier model of a Prius (when at the time they were rather unheard of a model and a technology in here) and so have actual experience of 5-6 years in using them in Sri Lankan conditions. My car is a old 1997 model Prius (as one in the photo above), which is the very first Prius model to come out of factories. Japan started to export Prius only in 2001. The recent models 2008-2010 are far more advanced and superb in features than my old poor car, yet the main principles of the hybrid concept is more or less same so answers can be the same for most of generic hybrid car questions. 

Let me list most frequent questions I got and their answers :

1) How easy is it to find parts in here ?
No big deal. At least for my model, almost all the parts I have replaced so far were compatible with other Toyota models. Namely Corolla 121 or Allion. Parts I have to replace/renew in last 6 years since I bought my car were Shock Absorbers, CV joint, spark plugs, lower arm bush, mounts, break pads etc. They were all compatible, as you know Toyota parts are the easiest to find in Sri Lanka.

2) How expensive were repairs/maintenance ?
It's exactly same as any other Toyota model. I mean servicing the vehicle, renewing parts etc. I didn't encounter needs for repairing the hybrid unit yet, but will come to that later.. So, as for all the other repairs which you encounter 99% of the time of normal vehicle repairing,  It was relatively cheap. Reason was mechanics in Sri Lanka are more familiar with Toyota. As mentione d above parts ere not expensive either (when compared to let's say Honda, Mazda etc)

3) How many kilometers does it do for a liter of petrol
For some reason most people are under the impression that Prius does about 40 kilo meters for a liter of patrol! completely not true!! May be the reason for this myth is in the manuals it says fuel consumption is 40mpg. Note, that means 40 miles per gallon! and gallon means a US gallon. this need to be converted to kilometer and liters. 40 mpg is 24 km/l and that is ideal lab condition expectation. In reality, the car was expected to do somewhere above just 20. While this is still very good and almost double the fuel efficiency of a normal car, it is no where near what some people assume a Prius to be. In the newer models expectation is to near the efficiency level of 50mpg. This would mean about 30 kilometers per liter. Hope an owner of a new Prius car would confirm for us whether this can be observable under normal Sri Lankan conditions.

As for my car, it did about 20 - 22 outstations and about 15 in the city traffic. Averaging about 17-18 per liter at every month. I was very happy  with that. Since people were so afraid to buy this car then (I bought that in 2005), it had a lesser market value, so I did not spend any additional amount to gain that fuel befit. It was a total save! Besides the amount I spend to buy the car was actually even less than then market value of then recent model of Corolla!! So I had reasons to be happy.

Over the years, fuel efficiency dropped a little. After 6 years now it is doing only about 18 outstations and 12 in city traffic. Still not so bad considering the car is now 14 years old and have now done about 120 000 Kilometers.

4) How far can you go in battery without using petrol
This question is entirely wrong. Prius can't go any distance without petrol, petrol needs to be in the tank at all times. This is not an electric vehicle. You can view it as an efficiently built petrol car with some fuel saving features. Some of those features are :

• High fuel efficient engine
• Body shape to reduce air resistance.
• Re generative braking. 
• Extra power get saved in a battery and will be used later
• Engine stops when the vehicle is idle in traffic
• Newer models can provide air conditioning from the batter power.
• LCD display with fuel consumption statistics.

So it's more correct to view a hybrid car as basically a normal petrol vehicle with few fuel saving features with the aid of a rechargeable battery among other things. I personally give lot of credit to the LCD display for high fuel efficiency as it helps us to find faults in our driving and help improve our driving habits to improve fuel efficiency. For instance, in the first week after buying the Prius I recorded just 10 Kilometers per liter. Once I get used to how to drive a Prius properly (in fact these techniques are true for any car), my fuel consumption reduced almost by 50% !  Basically you need to aggressively accelerate at the start, get into a comfortable speed quickly and then try to maintain that as a constant without pressing hard on the accelerator. This technique is called 'feathering' you give gas just enough to keep the current speed and not more.

Opposite of this is what most drivers do. Accelerate like crazy when ever possible and then brake like crazy. Lot of energy get wasted when we accelerate just to break few seconds later.  

Another false understanding on Prius is that people trying to go solely from battery as long as they could thinking that they are saving fuel. This is actual wrong! Once the battery discharges, then the car will have to waste petrol to get the battery charge again! This technique therefore provides no gain and even decrease the overall performance.  A mentioned above, when we try to drive in a constant speed without burning additional fuel, system will automatically decide to provide additional power via battery, this is the energy which  normally get wasted in ordinary vehicles.

5) What if the battery goes dead. how expensive is it to get imported ?
In the days I bought it, if the battery goes dead that would have been  a big issue for me since there were not many importers and the battery in 1997 model was a big heavy monster. I think it would have cost at least 2-3 hundred thousand to (2K-3K US$) get a new one from Japan, if not more. However battery never died, well not yet at least! Toyota is known to be very smug about this and say 'our battery never dies', (but we Buddhists should know better on that!). In my model, Toyota used to give a warranty of 160000 kilometers or 8 years for the battery! even though we don't get this in reconditioned Sri Lankan cars, this shows how confident they were on their batteries. The newer models should be even better! We all know how much dry fuel cell battery technology has improved since 1997!

Another thing is when I felt like battery performance is going down a bit, I used to go to a good friend of mine who had just the right equipments and know how to address the issue. (too bad I can't name him here due to  professional reasons from his side) Basically he could open up the battery, take down 40 odd individual small cells inside it and measure them for voltage. He says if one cell is defective, all the other cells after it will not charge properly and that's the reason of overall battery performance to go down. So he would just find the defective cell, charge it from the main (like I said he has equipments!) and reassemble the battery, problem gone! For the last 6 years I had to do this only once and he hasn't even charge any money for that! (Like I said he was a friend of mine!)

I have just mentioned above information to show the readers that there really is not a big problem to worry over. This is a technologically very advanced age and information can be found readily in internet. So there is nothing like a impossible technical problem when it comes to issues like these. Only reason I have about these batteries are that how are we going to recycle them in about 15-10 years of time from now. Batteries are very toxic and I hope there will be plans and places which does proper recycling, otherwise these batteries could cause lot harm to the environment to offset the good Prius is now doing with lowered emissions and lowered fuel consumption. This is a point most people pay little attention to.

Re-generative breaking mentioned above is the process where the hybrid car saves the additional kinetic energy at the time we are breaking in to a rechargeable battery. In normal vehicles, this energy get wasted as heat when we apply breaks. In Prius, a separate motor will work when we apply breaks. (that's why we hear that nice humming noise while breaking)  this motor will convert kinetic energy into electricity and save it in the battery for later use. Again, breaking need to be applied in a controlled manner for this system to work efficiently.

6) How good a car is this

This is a great car! On this you don't have to listen to anybody. Here is a simple test : Go to toyota site, check the prices of top range Toyota cars. You would see something like this : (prices in US$)
Corolla : 16K-18K
Camry :   20K
Prius :      22.5K  
Yaris :      13K
Avalon :    33K
RAV4  :    22K  

Prius is priced much higher than common models such as Corollo and Yaris. Even more expensive than Rav4 which is a SUV! Only Avalon is more expensive than Prius, but then Avalon is a super luxury vehicle which drink petrol (relative terms) if you are of that type.

So Prius is a expensive vehicle than Yaris or Corolla, yet due to tax breaks in Sri Lanka, a Prius cost less even than those economy Toyota models! Not to mention the amounts of money you can save on fuel afterwards! Therefore it's a definite attractive model to buy. In addition, Prius is possibly the most greenest of petrol / hybrid vehicles out there. It has been initially designed as a low emission vehicle to be environment friendly. It's a good part from the government to reduce tax and encourage people to go for the greener options like these.

Honda Hybrid models like Insight (World's first hybrid car If I'm not mistaken.) are also had to be good but I do not have hands on experience on those. Earlier Insight models used to be even better than earlier Prius models in terms of fuel efficiency but Insight lost market due to it being a 2 seater while Prius was categorized as a mid size sedan.

Got more questions on Prius... ? Feel free to ask!

PS :
Driving the Prius was always a very comfortable experience. Good handling, control, super sensitive breaking and power steering, short turning radius etc. Surprisingly pickup seems to be very good as well. Having battery is useful at hill climbing when you can get power from 2 sources. All this while saving the environment too ! In short I would recommend this car. However, according to what i know there is not much practical difference between 2009 model and 2010 model except in pricing. So going for 3rd generation 2009 model (which is lot advanced compared with 2nd generation 2008 model) seems to be the right choice.