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Would you buy a new petrol engine car today?

Passion, instruction, buying, care, maintenance and more, any form of vehicle discussion is welcome here
jackdaww
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Re: Would you buy a new petrol engine car today?

#389037

Postby jackdaww » February 23rd, 2021, 9:13 am

Nocton wrote:As there seems a lot of ignorance about how hybrids work, I add a few more words to my post.
When you run a petrol (or diesel car), especially in an urban area, you spend a lot of time slowing down and braking. e.g coming to a stop at traffic lights and then accelerating away when the lights change to green. The hybrid stores the energy from slowing down in the battery so it can be used in the acceleration phase. Otherwise that energy is lost as heat. That is why we get about 60mpg with our Auris 1.8l hybrid instead of about 40mpg with the petrol-only version.
The car has an electric motor as well as a petrol motor and the electronic clutch syncs both so that either or both can drive the wheels with a seamless and undetectable change. As my wife and I have driven automatic for 30 years, the automatic feature is a bonus for us.

The point I made also about hybrids is that they use energy which would otherwise be wasted - it is free. The electricity does not come from the grid. Electric cars get all their energy from the grid, so since at present it is mostly not green energy, they are helping as much with getting to zero emissions as the current hype suggests. And they will require a lot more grid capacity, which is yet to be built.


====================================

you believe the overun/braking savings gives a 20 mpg difference .

i contend the savings would amount to just a few mpg - my guess - and that would be more than swallowed up by carrying the extra weight of batteries , generators and motors .

:roll:

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Re: Would you buy a new petrol engine car today?

#389038

Postby richlist » February 23rd, 2021, 9:15 am

That s not entirely right, there are different types of hybrid. Some can be charged from the mains. Electric cars are not all charged from the grid, some can be charged from solar power.

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Re: Would you buy a new petrol engine car today?

#389049

Postby Mike4 » February 23rd, 2021, 9:33 am

Nocton wrote:As there seems a lot of ignorance about how hybrids work, I add a few more words to my post.
When you run a petrol (or diesel car), especially in an urban area, you spend a lot of time slowing down and braking. e.g coming to a stop at traffic lights and then accelerating away when the lights change to green. The hybrid stores the energy from slowing down in the battery so it can be used in the acceleration phase. Otherwise that energy is lost as heat. That is why we get about 60mpg with our Auris 1.8l hybrid instead of about 40mpg with the petrol-only version.
The car has an electric motor as well as a petrol motor and the electronic clutch syncs both so that either or both can drive the wheels with a seamless and undetectable change. As my wife and I have driven automatic for 30 years, the automatic feature is a bonus for us.

The point I made also about hybrids is that they use energy which would otherwise be wasted - it is free. The electricity does not come from the grid. Electric cars get all their energy from the grid, so since at present it is mostly not green energy, they are helping as much with getting to zero emissions as the current hype suggests. And they will require a lot more grid capacity, which is yet to be built.


Thank you for the expanded explanation, very illuminating.

So just to clarify, the only energy you put into your Auris is petrol? You can never charge it by plugging it in?

This is very impressive, getting 60mpg from the petrol, but I can see why they are not "the answer', as all your motoring is still fuelled by petrol. The electric car charged from the mains (or solar) has the potential to use no fossil fuel at all.

So is the Prius loved by private hire firms the same? I.e. runs exclusively on petrol? Or is it the type of hybrid just mentioned, that can be plugged into the mains (or solar) to charge?

richlist
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Re: Would you buy a new petrol engine car today?

#389070

Postby richlist » February 23rd, 2021, 10:13 am

Just to clarify....There are 3 main types of electric vehicles.
* BEV.....battery electric vehicle. Fully electric.
* PHEV....plug in hybrid electric vehicle. Has engine and electric. Battery charged by plugging into grid.
* HEV.....hybrid electric vehicle. Has engine which charges the storage battery. Does not plug into grid.

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Re: Would you buy a new petrol engine car today?

#389072

Postby Mike4 » February 23rd, 2021, 10:18 am

richlist wrote:Just to clarify....There are 3 main types of electric vehicles.
* BEV.....battery electric vehicle. Fully electric.
* PHEV....plug in hybrid electric vehicle. Has engine and electric. Battery charged by plugging into grid.
* HEV.....hybrid electric vehicle. Has engine which charges the storage battery. Does not plug into grid.


Not according to Nocton above. S/he says the engine in a HEV connects via a clutch to the wheels. No mention of the engine charging the battery.

richlist
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Re: Would you buy a new petrol engine car today?

#389083

Postby richlist » February 23rd, 2021, 10:38 am

There's a variety of HEV types & the degree to which each functions varies.

It's very unlikely that regenerative braking alone would be enough to provide sufficient battery charge.

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Re: Would you buy a new petrol engine car today?

#389092

Postby Dod101 » February 23rd, 2021, 11:03 am

Presumably the 60 mpg comes to some extent at least from the fact that the petrol engine is not working all the time. The car runs on electricity and when it does it is saving petrol, but then the petrol engine charges the batteries when required but that presumably does not need a great deal of petrol. I assume also that the car will run on petrol as required. but that the priority is for it to run on electricity.

I certainly would never have a plug in electric car; the range is not good enough and I could not be bothered except if I had access to one of these very fast chargers. I may change my car later this year assuming we are more or less back to 'normal' but at the moment I think it is going to be pure petrol although I will see if there is a hybrid which suits me.

Dod

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Re: Would you buy a new petrol engine car today?

#389101

Postby redsturgeon » February 23rd, 2021, 11:28 am

Dod101 wrote:Presumably the 60 mpg comes to some extent at least from the fact that the petrol engine is not working all the time. The car runs on electricity and when it does it is saving petrol, but then the petrol engine charges the batteries when required but that presumably does not need a great deal of petrol. I assume also that the car will run on petrol as required. but that the priority is for it to run on electricity.

I certainly would never have a plug in electric car; the range is not good enough and I could not be bothered except if I had access to one of these very fast chargers. I may change my car later this year assuming we are more or less back to 'normal' but at the moment I think it is going to be pure petrol although I will see if there is a hybrid which suits me.

Dod


I have had both a non plug in and a plug in hybrids.

The Lexus I had was non plug in and would do about 2 miles on pure electric if you wanted, otherwise it would operate automatically as has been explained above. It had a CVT box and was OK to drive but not very sporty. It was the most reliable (and possibly most boring) car I have ever owned.

The BMW I have now has a normal auto box, a three cylinder petrol engine driving the front wheels and an electric motor driving the rear. I can choose to operate it as electric only for about 20 miles, petrol only or as a combination which gives AWD.

During the first lockdown it was great, we only drove it locally and therefore went for three months on electric only...much cheaper than running on petrol. I have a drive and a 7kw charger that I plug in anytime the car is parked. If I need to go on a long journey then I just use it as I would any ICE car.

For me this is the best of both worlds though I can understand why it would not suit everybody. I much prefer it to the Lexus hybrid approach.

John

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Re: Would you buy a new petrol engine car today?

#389158

Postby GoSeigen » February 23rd, 2021, 1:02 pm

Mike4 wrote:
richlist wrote:Just to clarify....There are 3 main types of electric vehicles.
* BEV.....battery electric vehicle. Fully electric.
* PHEV....plug in hybrid electric vehicle. Has engine and electric. Battery charged by plugging into grid.
* HEV.....hybrid electric vehicle. Has engine which charges the storage battery. Does not plug into grid.


Not according to Nocton above. S/he says the engine in a HEV connects via a clutch to the wheels. No mention of the engine charging the battery.


Probably every HEV has its own quirks.

The Prius which Mike4 mentioned was a brilliant piece of engineering. It charged the battery using the engine. In simple terms a planetary gear system distributed power between the wheels, the alternator, the petrol engine and the electric motor depending on where it was needed, with computer control of the power output of the engine and motor based on the charge state of the batteries, the acceleration or braking demand (changing kinetic energy) and the changing potential energy (going up- or downhill). So the Prius could charge the battery while slowing down, converting kinetic energy back to electrical; or while going downhill, converting potential energy to electrical; or by running the engine, converting fossil fuel into electrical energy. A large part of their efficiency came because the petrol engine 1. could be smaller (thus lighter, more efficient), 2. was optimised for a particular role i.e. cruising not accelerating and 3. only charged the battery while running at its maximum efficiency.

Here's a simple scenario to contrast the Prius hybrid with a petrol vehicle: imagine starting from a traffic light, reaching a steady speed for a few minutes, then stopping at the next light.

1. The traditional petrol car's engine would be larger than the hybrid's because it would be required to accelerate the vehicle unaided. It would also be designed with torque as well as power in mind, i.e. with some efficiency compromises. As the car accelerated the efficiency of the engine would vary (i.e. become less than optimal) depending on the engine speed but mitigated by changing gear (but... heavy gearbox). At cruising speed the engine is still running wasting a small amount of fuel. While braking for the next light, all the speed of the car becomes heat in the brakes or engine, which is still running while slowing and stopped.

2. The Prius hybrid sets off and mostly accelerates with its electric motor, which efficiently produces high torque at low speeds. The petrol engine helps but can be smaller and work efficiently because of the contribution of the electric motor. The control computer varies the electric motor output while gaining speed to keep the petrol engine in its efficient sweet spot. While cruising the engine continues running in its sweet spot, recharging the batteries whose energy has been used for acceleration. When the charging is complete the petrol motor is turned off entirely, the small amount of power needed to overcome air resistance can be supplied by the electric motor. If the speed/slope is such that the computer judges the petrol engine would be more efficient than the electric motor, then the former is restarted and the electric motor's contribution reduced. As the car slows for the lights the engine is still turned off while the battery is charged further using the reducing kinetic energy. The engine remains off while waiting at the lights.

Incidentally, the Prius also lacked a starter motor because the electrical drive motor could start the engine. Alternatively you could think of the drive motor as an oversized starter motor connected directly to the drive train via those planetary gears. Thinking about it, the only real additional part for the Prius is its large solid state battery, otherwise the parts list is similar:
-it has a smaller acid battery than the petrol car (not used for starting the engine)
-it has a smaller, more efficient petrol engine
-it has a larger electric motor, used for propulsion as well as starting the engine
-it has a planetary gear system and computer controlled power versus a gearbox (manual or auto)
-its brake pads last longer, but it has the additional battery pack.


That's probably way more than you wanted to know but hopefully gives and idea of the many ways that efficiency was improved by the Prius's design.

GS

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Re: Would you buy a new petrol engine car today?

#389168

Postby swill453 » February 23rd, 2021, 1:12 pm

GoSeigen wrote:... When the charging is complete the petrol motor is turned off entirely, the small amount of power needed to overcome air resistance can be supplied by the electric motor.

The only issue I have with your explanation is that at "cruising" speed quite a large amount of power is needed to overcome air resistance. Before too long the battery will be exhausted and the petrol engine will be needed.

Scott.

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Re: Would you buy a new petrol engine car today?

#389178

Postby ReformedCharacter » February 23rd, 2021, 1:37 pm

swill453 wrote:
GoSeigen wrote:... When the charging is complete the petrol motor is turned off entirely, the small amount of power needed to overcome air resistance can be supplied by the electric motor.

The only issue I have with your explanation is that at "cruising" speed quite a large amount of power is needed to overcome air resistance. Before too long the battery will be exhausted and the petrol engine will be needed.

Scott.

Yes, it rises at the cube of speed AFAIK.

RC

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Re: Would you buy a new petrol engine car today?

#389179

Postby wilbobob » February 23rd, 2021, 1:39 pm

Added to Go Seigens post above, the Prius also uses a modified Atkinson Cycle instead of the usual Otto Cycle
see here https://mag.toyota.co.uk/toyota-use-atk ... e-engines/

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Re: Would you buy a new petrol engine car today?

#389180

Postby AF62 » February 23rd, 2021, 1:40 pm

Dod101 wrote:I certainly would never have a plug in electric car; the range is not good enough and I could not be bothered except if I had access to one of these very fast chargers.


How much range do you want - Is 200 - 250 miles not enough?

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Re: Would you buy a new petrol engine car today?

#389183

Postby dealtn » February 23rd, 2021, 1:43 pm

AF62 wrote:
Dod101 wrote:I certainly would never have a plug in electric car; the range is not good enough and I could not be bothered except if I had access to one of these very fast chargers.


How much range do you want - Is 200 - 250 miles not enough?


Not for me, I would likely need 2-3 times that.

Although I don't need a new car, and displaying my "green credentials" happy to continue to use an older, perfectly working, older model rather than replace unnecessarily.
Last edited by dealtn on February 23rd, 2021, 1:46 pm, edited 1 time in total.

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Re: Would you buy a new petrol engine car today?

#389184

Postby nmdhqbc » February 23rd, 2021, 1:45 pm

richlist wrote:* HEV.....hybrid electric vehicle. Has engine which charges the storage battery. Does not plug into grid.


Maybe some do charge from the engine as well but the main point is that they charge regen brakes when slowing down. As do BEV's and PHEV's. this is what makes the whole "self charging hybrid" Toyota spout out so infuriating. they all self charge using regen!!! and for a non-plug in hybrid ALL the energy came from petrol originally. Just a good efficiency device but now there's better options.

I think the grid is more green that some think and will only get greener with time. There's a nice chart from 2019 on the page below. There's much evidence that BEV's are better for the environment. For me it's just a question of if the cost works out better which depends on your milage and massively on whether you have a place to charge at home. Charging overnight with the right type of tarrif is way cheaper than charging out and about all the time.

https://www.carbonbrief.org/analysis-uk ... first-time

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Re: Would you buy a new petrol engine car today?

#389187

Postby GoSeigen » February 23rd, 2021, 1:53 pm

swill453 wrote:
GoSeigen wrote:... When the charging is complete the petrol motor is turned off entirely, the small amount of power needed to overcome air resistance can be supplied by the electric motor.

The only issue I have with your explanation is that at "cruising" speed quite a large amount of power is needed to overcome air resistance. Before too long the battery will be exhausted and the petrol engine will be needed.

Scott.


Depends where you're cruising Scott. I was somewhere in Wandsworth I think.

:-)

GS
P.S. Do feel free to quote the next sentence which was relevant!!
P.P.S. On some boring journeys I'd amuse myself by seeing how far I could go without triggering the petrol engine... sad, I know!

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Re: Would you buy a new petrol engine car today?

#389213

Postby AF62 » February 23rd, 2021, 3:03 pm

dealtn wrote:
AF62 wrote:
Dod101 wrote:I certainly would never have a plug in electric car; the range is not good enough and I could not be bothered except if I had access to one of these very fast chargers.


How much range do you want - Is 200 - 250 miles not enough?


Not for me, I would likely need 2-3 times that.


You drive 500 to 750 miles in one go without taking a break?

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Re: Would you buy a new petrol engine car today?

#389214

Postby dealtn » February 23rd, 2021, 3:05 pm

AF62 wrote:
dealtn wrote:
AF62 wrote:
How much range do you want - Is 200 - 250 miles not enough?


Not for me, I would likely need 2-3 times that.


You drive 500 to 750 miles in one go without taking a break?


A break not long enough to "recharge", yes. Or not convenient to recharge sometimes.

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Re: Would you buy a new petrol engine car today?

#389219

Postby Dod101 » February 23rd, 2021, 3:21 pm

AF62 wrote:
Dod101 wrote:I certainly would never have a plug in electric car; the range is not good enough and I could not be bothered except if I had access to one of these very fast chargers.


How much range do you want - Is 200 - 250 miles not enough?


Certainly not if I then have to find a charger and it is not very fast even if I do find one. I can put 60 litres of fuel (range 450 or so miles) in my tank in about 10 minutes all told. I regularly (when not in lockdown obviously) will travel 300/350 miles in one go and of course can do that without even needing to refuel en route.

Dod

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Re: Would you buy a new petrol engine car today?

#389220

Postby AF62 » February 23rd, 2021, 3:25 pm

Dod101 wrote:
AF62 wrote:
Dod101 wrote:I certainly would never have a plug in electric car; the range is not good enough and I could not be bothered except if I had access to one of these very fast chargers.


How much range do you want - Is 200 - 250 miles not enough?


Certainly not if I then have to find a charger and it is not very fast even if I do find one. I can put 60 litres of fuel (range 450 or so miles) in my tank in about 10 minutes all told. I regularly (when not in lockdown obviously) will travel 300/350 miles in one go and of course can do that without even needing to refuel en route.

Dod


Personally I wouldn't feel safe driving 300/350 miles non-stop and prefer to take a cup of coffee break after a 100/150 miles, but I accept everyone is different.


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