Hybrids - anything to watch for?
Discussion
I got 68 mpg out of the Yaris Hybrid I tried out, pretty impressive. I think the Toyota is the only full hybrid, and really the only hybrid worth looking at. On the newer ones, the batteries are not in the boot, so more boot space and less chance of a write off in a rear end smash. Diesels look good on MPG only, they are expensive to maintain, there are loads of things to go wrong ( and they do), derv is more expensive and they go dagadagadagadaga.
Andy665 said:
Not so - Toyota use an electronic CVT gearbox - still noowhere near as good as a conventional auto but it gives them the ability to maximise the efficiency of the powertrain
No so Andy - the Prius doesn't have a gearbox as such. It's not CVT. It's just classed as a CVT for tax and licence reasons.Edited by Andy665 on Thursday 2nd January 12:29
Toyota use Synergy drive, and (as others have pointed out) you'd best Google "Prius PSD" to see details of the epicyclic differential which in a HSD replaces the gearbox.
fatboy b said:
Friends of ours have just bought an 11 plate Jazz hybrid. They are quite disappointed with the economy so far with a mixture of short and long journeys. Averaging 48mpg. The o/h and her Seat 2.0tdi Ibiza is getting high 50s - low 60s.
I don't know why anyone expects better fuel economy from a Hybrid. You are carrying around 2 engines, and with 2 exceptions all the power still has to come from the petrol.Exception 1: Plug-in hybrids - some of the power can come from the electric socket, but not a lot.
Exception 2: Some of the petrol's power can be reclaimed by gentle braking (using the re-generative feature) but typically not a lot, it depends on your mix and style of driving.
I believe the new Prius (post 2012) if plug in hybrid will manage a claimed 12 miles on battery only. Now if you had a 5 mile drive to the train station to commute every day I can see the appeal. Fewer cold start, enriched running,engine not reaching operating temperature etc. This makes sense and you still have a petrol powered unlimited range. Now the electric only Renault Zoe can now be bought for £13000 secondhand with a claimed range of 145 miles ( must be at least 80 actual?) it would be practical for many users, however how do you charge it if you live in London if you have no offroad parking?, not sure how the battery lease is transferred?. Warranty on the Zoe is 100,000 or 4 years, service is 18,000 which is about as big an interval as is sensible.
M4cruiser said:
I don't know why anyone expects better fuel economy from a Hybrid. You are carrying around 2 engines, and with 2 exceptions all the power still has to come from the petrol.
Exception 1: Plug-in hybrids - some of the power can come from the electric socket, but not a lot.
Exception 2: Some of the petrol's power can be reclaimed by gentle braking (using the re-generative feature) but typically not a lot, it depends on your mix and style of driving.
Not quite true, any surplus power being generated by the engine and not being used will be channelled back to the batteries for later use - it's surprising how much this providesException 1: Plug-in hybrids - some of the power can come from the electric socket, but not a lot.
Exception 2: Some of the petrol's power can be reclaimed by gentle braking (using the re-generative feature) but typically not a lot, it depends on your mix and style of driving.
It amazes me how many people think that the Toyota / Lexus hybrid system provides only 1.6 miles of electric only capability, common sense should dictate that's its 1.6 miles at a time, dependent on the journey that 1.6 miles could be repeated many times in the 1980s the public how to re-educate themselves to get the vest out of the 'new fangled' diesel - the same is needed to get the best out of hybrid, little things like accelerating downhill and coasting as much as possible uphill perhaps contradicts logic but can make a decent positive difference with hybrid, similarly more anticipation and earlier, gentle braking has a major effect
Andy665 said:
Not quite true, any surplus power being generated by the engine and not being used will be channelled back to the batteries for later use - it's surprising how much this provides
Yes Andy it may do this, but the point is that the electric (battery) charge generated in this way has come from the petrol.But the Prius will only do this (i.e. use the petrol engine to turn MG1 to charge the battery) when it needs to; if the battery has enough charge then the petrol engine gets switched off until it's needed. And then MG1 uses some of the battery's charge to start the petrol engine again!
But I agree your point of needing to learn how to get the best out of a hybrid. And I know from experience that some (sales / training) people simply don't do that - perhaps they don't know themselves!
M4cruiser said:
Yes Andy it may do this, but the point is that the electric (battery) charge generated in this way has come from the petrol.
But the Prius will only do this (i.e. use the petrol engine to turn MG1 to charge the battery) when it needs to; if the battery has enough charge then the petrol engine gets switched off until it's needed. And then MG1 uses some of the battery's charge to start the petrol engine again!
But I agree your point of needing to learn how to get the best out of a hybrid. And I know from experience that some (sales / training) people simply don't do that - perhaps they don't know themselves!
But - if the car in question was not a hybrid this surplus energy from the petrol engine would be simply lost to the environmentBut the Prius will only do this (i.e. use the petrol engine to turn MG1 to charge the battery) when it needs to; if the battery has enough charge then the petrol engine gets switched off until it's needed. And then MG1 uses some of the battery's charge to start the petrol engine again!
But I agree your point of needing to learn how to get the best out of a hybrid. And I know from experience that some (sales / training) people simply don't do that - perhaps they don't know themselves!
The lack of knowledge / understanding of sales people is concerning - I have heard at least one sales person admit that he drives everywhere in B mode as he'd been told that this stood for boost whereas obviously B is designed to enhance the feeling of engine braking
It did beg the question of how many hybrid purchasers had been advised to drive permanently in B mode
Edited by Andy665 on Saturday 4th January 20:45
M4cruiser said:
Andy665 said:
Not so - Toyota use an electronic CVT gearbox - still noowhere near as good as a conventional auto but it gives them the ability to maximise the efficiency of the powertrain
No so Andy - the Prius doesn't have a gearbox as such. It's not CVT. It's just classed as a CVT for tax and licence reasons.Edited by Andy665 on Thursday 2nd January 12:29
Toyota use Synergy drive, and (as others have pointed out) you'd best Google "Prius PSD" to see details of the epicyclic differential which in a HSD replaces the gearbox.
M4cruiser said:
I don't know why anyone expects better fuel economy from a Hybrid. You are carrying around 2 engines, and with 2 exceptions all the power still has to come from the petrol.
Exception 1: Plug-in hybrids - some of the power can come from the electric socket, but not a lot.
Exception 2: Some of the petrol's power can be reclaimed by gentle braking (using the re-generative feature) but typically not a lot, it depends on your mix and style of driving.
It seems to me, that the better fuel economy of the Toyota hybrid system over a non-hybrid comes from the following.Exception 1: Plug-in hybrids - some of the power can come from the electric socket, but not a lot.
Exception 2: Some of the petrol's power can be reclaimed by gentle braking (using the re-generative feature) but typically not a lot, it depends on your mix and style of driving.
Firstly, you can optimise the ICE design for fuel efficiency rather than outright power and torque, because you have an electric drive to fill in any gaps in ICE output, and the design of the PSD means that there is only a very loose coupling between the speed of the ICE and the speed of the final drive. Hence the use of an (efficient) Atkinson cycle ICE.
Secondly, the fuel efficiency of ICEs varies with speed. Because ICE speed and final drive speed are not directly correlated, you can often run the ICE at the optimal speed, rather than the speed required to give a certain final drive. For example, it may be more fuel efficient to run the ICE faster than required and store the surplus energy in the battery for use later.
Thirdly, you have regen. As mentioned you have regen braking; press the brake pedal gently and instead of using the mechanical brakes, the system recovers kinetic energy and stores it in the battery for use later. In addition to this, when you coast (release the accelerator) in a conventional car, the fuel supply is cut off but the ICE is still connected to the wheels through the transmission, and so you are wasting energy by essentially running the ICE as a big air compressor (this is "engine braking"). With the PSD the ICE doesn't spin during coasting. Instead, the kinetic energy is again recovered and stored, and this slows the car down giving a sensation of engine braking (making it feel like a normal car). The "B" mode increases the force of engine braking for hills etc.
Fourthly, the electric mode gives you stop-start for free, and since all the ancilliaries are electrically powered, and since the battery is massive compared to the battery in a normal car, the ICE can spend more time "off" than in other cars. Many other cars have stop-start now, but the ICE has to kick in whenever there is a non-trivial power demand, and if you are stationary, much of the energy produced by the ICE is wasted in this scenario.
TLDR version: it's true that nearly all the energy is ultimately coming from the ICE anyway. But having an electric drive allows you to use a more fuel efficient ICE design, and also allows you to buffer the ICE output, meaning that you can run the ICE in a more fuel efficient manner. Plus you have regen.
This is specific to the Toyota system, the current Honda system does not tick all the boxes (although their next-gen system is apparently coming soon).
Andy665 said:
Not so - Toyota use an electronic CVT gearbox - still noowhere near as good as a conventional auto but it gives them the ability to maximise the efficiency of the powertrain
As he said the Toyota HYBRID SYNERGY DRIVE is totally different to CVT, it's a power split devise not gear ratio alterer.Edited by Andy665 on Thursday 2nd January 12:29
M4cruiser said:
I don't know why anyone expects better fuel economy from a Hybrid. You are carrying around 2 engines, and with 2 exceptions all the power still has to come from the petrol.
Exception 1: Plug-in hybrids - some of the power can come from the electric socket, but not a lot.
Exception 2: Some of the petrol's power can be reclaimed by gentle braking (using the re-generative feature) but typically not a lot, it depends on your mix and style of driving.
Because the engines can run more efficient cycles (Prius Atkinson), the engine can be downsized and can recapture energy.Exception 1: Plug-in hybrids - some of the power can come from the electric socket, but not a lot.
Exception 2: Some of the petrol's power can be reclaimed by gentle braking (using the re-generative feature) but typically not a lot, it depends on your mix and style of driving.
'Anyone' expects better fuel economy as they are not Clarkson morons? And that's what happens in the real world!
Pixelpeep said:
early toyotas had a notoriously expensive battery unit - £9000 to replace. Most rear end shunts resulted in the car being written off if the batteries got the slightest touch.
Honda units are much much smaller because they have less capacity - IIRC they were around £700 to replace.
Honda put a 5 year warranty on all the hybrid tech (not sure if it's transferable) because that was the expected life of the battery to remain efficient. - they do last beyond this but they slowly diminish.
one thing, especially with the honda tech - no good if you do motorway mileage. They regenerate using braking etc so if you drive, at a steady 70-80 for any reasonable length of time you will be getting minimal help from the batteries and therefore it will be the same as driving a 1.3 at 70mph (not very good for mpg)
The CVT gearboxes are very smooth but the moment you want to make progress you lose it all through slip.
What is this drivel? The Prius had a 1.3 kWh battery using Panasonic d cell batteries in the gen1.... Same as honda around 0.6kWh.... Ie half the batteries yet you are citing 15 times cost !?!?Honda units are much much smaller because they have less capacity - IIRC they were around £700 to replace.
Honda put a 5 year warranty on all the hybrid tech (not sure if it's transferable) because that was the expected life of the battery to remain efficient. - they do last beyond this but they slowly diminish.
one thing, especially with the honda tech - no good if you do motorway mileage. They regenerate using braking etc so if you drive, at a steady 70-80 for any reasonable length of time you will be getting minimal help from the batteries and therefore it will be the same as driving a 1.3 at 70mph (not very good for mpg)
The CVT gearboxes are very smooth but the moment you want to make progress you lose it all through slip.
A 1.3 ending in the insight/Jazz drives like a 1.5 but with more throttle on motorway this helps economy due to reduced friction and pumping losses also helped by CVT allowing a low engine speed. No alternator allows you to manage electrical load better. The extra mass of a battery on the trunk.... No worse than a cast iron block , turbo , DPF, inter cooler and high pressure fuel pump....
Also CVT gearboxes that slip are broken.
V400TC said:
Watch out you don't become the person to avoid whom talks of nothing but how much ££ he saves driving a hybrid.
Horses for courses and we can all not like the same things
Smugness and being a crashing bore are the things to avoid the most I would say.
Now where are the keys to my car.
Damn it! beaten to it - also watch out for the urge to wear sandals, grow a beard and stop eating meat because the "wasteful production methods" Horses for courses and we can all not like the same things
Smugness and being a crashing bore are the things to avoid the most I would say.
Now where are the keys to my car.
In all seriousness, I have driven a prius and a civic IMA and was secretly quite impressed with both, not enough to want or buy one, but impressed none the less. In the trade there is little to complain about with the prius other than they tend to seize brake calipers - I hear very few horror stories but then later down the line there could be problems but it really depends how older car you are thinking of. That said some prius are now 10years old and still running without issue
Some interesting points above, highlighting that HSD is very different to "normal" petrol or diesel, whether CVT or not.
Another point to watch though is that last time I drove a Prius it started the engine during a long stop, because the battery needed charging! Not quite the same as a petrol car with a start/stop system. I believe the Toyota system keeps the battery in the middle of its charging capacity, i.e. doesn't let it get anywhere near full or empty.
Yes the ICE in the Prius can often run at its optimum speed, but not all the time, because it's variably geared to the MG2 motor that drives the wheels, but the difference must necessarily be soaked up by the MG1 (unless the ICE is declutched and switched off).
What I'm really saying is that I like the Prius, but I don't expect it to be a lot more economical than an Avensis petrol.
Another point to watch though is that last time I drove a Prius it started the engine during a long stop, because the battery needed charging! Not quite the same as a petrol car with a start/stop system. I believe the Toyota system keeps the battery in the middle of its charging capacity, i.e. doesn't let it get anywhere near full or empty.
Yes the ICE in the Prius can often run at its optimum speed, but not all the time, because it's variably geared to the MG2 motor that drives the wheels, but the difference must necessarily be soaked up by the MG1 (unless the ICE is declutched and switched off).
What I'm really saying is that I like the Prius, but I don't expect it to be a lot more economical than an Avensis petrol.
M4cruiser said:
Some interesting points above, highlighting that HSD is very different to "normal" petrol or diesel, whether CVT or not.
Another point to watch though is that last time I drove a Prius it started the engine during a long stop, because the battery needed charging! Not quite the same as a petrol car with a start/stop system. I believe the Toyota system keeps the battery in the middle of its charging capacity, i.e. doesn't let it get anywhere near full or empty.
Yes the ICE in the Prius can often run at its optimum speed, but not all the time, because it's variably geared to the MG2 motor that drives the wheels, but the difference must necessarily be soaked up by the MG1 (unless the ICE is declutched and switched off).
What I'm really saying is that I like the Prius, but I don't expect it to be a lot more economical than an Avensis petrol.
The Prius ICE also starts sometimes if cabin heat is needed. Most real world mpg databases show that the Prius is about 35-38% more economical than an Avensis petrol (which is pretty economical for a conventional petrol car).Another point to watch though is that last time I drove a Prius it started the engine during a long stop, because the battery needed charging! Not quite the same as a petrol car with a start/stop system. I believe the Toyota system keeps the battery in the middle of its charging capacity, i.e. doesn't let it get anywhere near full or empty.
Yes the ICE in the Prius can often run at its optimum speed, but not all the time, because it's variably geared to the MG2 motor that drives the wheels, but the difference must necessarily be soaked up by the MG1 (unless the ICE is declutched and switched off).
What I'm really saying is that I like the Prius, but I don't expect it to be a lot more economical than an Avensis petrol.
M4cruiser said:
Some interesting points above, highlighting that HSD is very different to "normal" petrol or diesel, whether CVT or not.
Another point to watch though is that last time I drove a Prius it started the engine during a long stop, because the battery needed charging! Not quite the same as a petrol car with a start/stop system. I believe the Toyota system keeps the battery in the middle of its charging capacity, i.e. doesn't let it get anywhere near full or empty.
Yep. It seems that there are a number of conditions that can cause the ICE to fire up:Another point to watch though is that last time I drove a Prius it started the engine during a long stop, because the battery needed charging! Not quite the same as a petrol car with a start/stop system. I believe the Toyota system keeps the battery in the middle of its charging capacity, i.e. doesn't let it get anywhere near full or empty.
- Engine is below operating temperature
- Need more power than can be provided by electric mode (e.g. strong acceleration, driving above 40mph)
- Battery running low, and insufficient energy coming in through regen
- Electric cabin heater can't supply enough heat
This means that fuel consumption during the first few minutes is pretty abysmal, but then starts to climb rapidly as you cover some distance in EV mode. My mum lives half a mile away, and if I incur the ridicule of the PH masses by driving it instead of walking it, I get overall 50mpg in cold weather. If it's warm weather, I get infinite mpg
The ICE will also kick in if you need extra cabin heat. The Prius cabin heater is electric, supplemented with engine heat. Generally, once the cabin is at temperature, only the electric heater is needed to keep it constant, and the ICE can stay off. However, if it's cold outside, and you tell the car to get to room temperature or defrost the screen, the ICE will kick in, since the electric heater can't do it on its own, it isn't powerful enough. The engine heat is extracted and the power is used to charge the battery.
The car seems to keep the battery charge between 20% and 80% (assuming the battery gauge is linear). If the battery goes below 20%, and is on a downward trend, it will start the ICE, use it to move the car and harvest any surplus power.
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