Driving a hybrid

[stefan einz]

I have recently taken delivery on my first hybrid car, principally for commuting into London. It is a Panamera S E-Hybrid, which is a plug-in hybrid (i.e. is capable of being recharged from a power socket, as well as by the engine).

It's been an interesting time beginning to figure out the most fuel efficient way to drive the car - e.g. what proportion of the journey to do in full E-mode (it will do about 10-11 miles of urban driving in that mode), or in normal, hybrid mode (where the system decides the best combination of battery and petrol power (within the limit of not depleting the battery too far)).

But what is also interesting is the adaptations I've had to / chosen to make to my driving style. One of the main features of the car is that it will coast whenever it can. So it will switch off the engine almost as soon as one lifts off the gas pedal. There is a small amount of "engine" braking, due to the electric motor, which remains engaged, but there is far less engine braking overall than a normal car. Braking is also different due to the fact the brakes work on a combination of regenerative braking (via the e-motor) and hydraulic braking. The pedal feel can vary as the car comes to a stop.

In adapting to these features, I've been lifting off earlier than I otherwise would, to provide a longer coasting period and to allow for the reduced engine braking. I am also braking earlier and more softly, to use the regenerative braking to best effect (i.e. not bring in the normal brakes).

It's also required a degree of discipline not to be distracted by all the fancy power transfer displays!

In any event, it's a taste of the future. Certainly the E-mode in London is fantastic. The electric motor generates just under 90hp, so it is not fast, but just brisk enough for London traffic (given the car weights 2 tonnes). But what is lovely is the supremely quiet and smooth progress one can make. Of course, one final thing of which I am aware is the fact the car makes almost no noise, so I am more alert to pedestrians and cyclists potentially not being aware of the car's presence.

So, an interesting experience, and one that is fiscally good too - £5k contribution from the Government to buy the car; no congestion charge; no VED and a 100% writing down allowance (as it is a business asset in my firm). And hopefully I will find a way to drive it to its theoretical best mpg of 90 plus!

Cheers

[kfae8959]

Thanks for these reflections, stefan. I've driven some hybrids with very odd-feeling brakes, probably none of them as good as the Panamera's! Most of my hybrid driving has been in the US, where the street patterns in towns and cities mean frequent stops at traffic lights and crossroads. But the cars I've driven don't coast: they will only cut the engine when stopped. That has set me wondering whether I should reverse my usual plan, which is to keep the car rolling if possible at traffic lights by taking the speed off early, and instead get it stopped as soon as possible to maximise the time the engine can stop.

The profusion of different systems and variants in modern cars seems to mean that we have to be more adaptable and have more understanding of our machinery now than ever before!

David

[TR4ffic]

I’m now on my 3rd Prius (all through the company for the reasons given above) – 5 ½ years and 120k+ miles in total… Mine isn’t the plug-in model, just the standard hybrid with battery charge coming from the engine or regeneration. I consistently get ave 60-65mpg no matter what I do and I currently have a 130 mile round trip daily commute mostly on motorway – M6/M1.

Like the Panamera, the Prius has an EV mode but I leave it in standard hybrid mode and let it sort itself out as to whether it wants engine or electric or both. As soon as you reach a constant speed, lift off the gas or go downhill the engine will stop but I don’t class this as ‘coasting’ – You’re in drive, it’s just the way the car works. You do get some engine braking when you lift off but, as well as drive ‘D’, the Prius also has a ‘B’ position on the shift that applies engine braking – instead of the engine being off and disengaged from the transmission/wheels, I assume a clutch type mechanism engages the engine and ‘locks’ the transmission ratio (it’s a CVT ‘box).

To get the best out of the hybrid system and good mpg I find the best thing to do when setting off from rest is to accelerate reasonably swiftly up to your desired speed and then, if you lift off the gas slightly, you can maintain the speed and the electric/hybrid system really comes into play – The idea being to reduce the length of time the engine is on and working hard-ish… When on the open road or motorway I can get better mpg when controlling the gas myself than using cruise control.

When accelerating, the system does take a bit of getting used to and to understand what it’s doing. The accelerator is ‘fly by wire’ – not directly connected to the engine. What I think its doing is… Engine revs are set by the ECU and, I assume, are set for the most efficient engine speed/load as, when engine is on but the electric motor is not required, any excess power from the engine is used to charge the batteries. So engine revs can sometimes seem unnaturally high and, also, for a set throttle position when accelerating engine revs can change as speed increases and/or load changes.

I see hybrids as the way forward in the medium term – nearly all manufacturers are introducing some form of hybrid – until full electric can take over as range and charging times become acceptable. I saw an article last week from some technology convention that showed a mobile phone battery going from flat to fully charged in 30-40 seconds. Article here http://www.eetimes.com/document.asp?doc_id=1321873& which includes some innovation in electric motors/drivetrain.

[Ancient]

I see hybrids as the way forward in the medium term – nearly all manufacturers are introducing some form of hybrid – until full electric can take over as range and charging times become acceptable. I saw an article last week from some technology convention that showed a mobile phone battery going from flat to fully charged in 30-40 seconds. Article here http://www.eetimes.com/document.asp?doc_id=1321873& which includes some innovation in electric motors/drivetrain.

I see hybrids and 'full electric' as places where manufacturers are experimenting with technologies before using them as applicable in 'mainstream' cars, meaning that 'mainstream' will become more like hybrids gradually and the label itself will eventually disappear. I had a second generation Prius for four years and the fuel performance by the end of that time was matched by the Skoda Superb Greenline estate I now have. Both stop-start technlogy (love or hate the details of how it is implemented) and regenerative braking are making it into 'mainstream' cars and IMO once battery technology improves so that electric assist doesn't require a bank of them under the seat, so will this. That F1 racers now use this technology instead of 2.4l V8s (http://www.formula1.com/news/features/2014/1/15408.html) is an indication of the direction manufacturers are looking.

With regard to the two levels of engine braking in the Prius, I found it interesting to have three different rates of slowing (normal lift of and eventually run out of momentum, engine Braking and brakes), all to consider in the approach to a stop for example. Most fun was the smoothness of the CVT which would worry people who tried to race away from lights, causing extreme dipping as the 'eco-car' pulled away whenever they changed gear
I certainly agree that 'accelerate and lift off' was the best (economy) way to drive the Prius, but this is not easy to keep to on 'interesting' roads where I now live: Definately a car for motorway style journeys IMO.

[7db]

Of course, one final thing of which I am aware is the fact the car makes almost no noise, so I am more alert to pedestrians and cyclists potentially not being aware of the car's presence.

I nearly died a thousand deaths as a pedestrian in London when the Prius first came out. Bloody things can't half sneak up on you.

[TheInsanity1234]

Of course, one final thing of which I am aware is the fact the car makes almost no noise, so I am more alert to pedestrians and cyclists potentially not being aware of the car's presence.

I nearly died a thousand deaths as a pedestrian in London when the Prius first came out. Bloody things can't half sneak up on you.

I must say, I've never had a problem with the quietness of a electric car or hybrid as I'm deaf, so I've naturally been much more visually aware.

Having said that, I once saw someone just step into the road and nearly get run over by a G-Wiz.

Perhaps electric vehicles will help reduce pollution but after a while there might not be any humans to drive the cars because we've all been run over by the electric cars!

[stefan einz]

Having said that, I once saw someone just step into the road and nearly get run over by a G-Wiz.

Having seeing a G-Wiz a few times in London, I'd reckon it would come off second best in a collision with any reasonably strong person. Truly dreadful thing.

[7db]

I'm glad it's not just me that has an almost irresistable urge to go at them with my shoulder when I see them, and see how they roll...

[TheInsanity1234]

I'm glad it's not just me that has an almost irresistable urge to go at them with my shoulder when I see them, and see how they roll...

+1


They're terrible little plastic boxes!

[WhoseGeneration]

I must say, I've never had a problem with the quietness of a electric car or hybrid as I'm deaf, so I've naturally been much more visually aware.

Having said that, I once saw someone just step into the road and nearly get run over by a G-Wiz.

Perhaps electric vehicles will help reduce pollution but after a while there might not be any humans to drive the cars because we've all been run over by the electric cars!

So, not only are you not yet 17 but happy to engage in conversation, using perfect English, on a 'site about a very specific discipline with others who are mainly much older than you but now you reveal that you are deaf.
I doff my hat to you, you'll go far in life, whatever you decide to do.

[TheInsanity1234]

So, not only are you not yet 17 but happy to engage in conversation, using perfect English, on a 'site about a very specific discipline with others who are mainly much older than you but now you reveal that you are deaf.
I doff my hat to you, you'll go far in life, whatever you decide to do.

Well, thanks!
Well, after finishing my GCSEs I intend to do my A-levels (Physics, Chemistry, Maths and Further Maths) then progress into a Physics course at university and hopefully get a PhD then become a lecturer in a university, or a teacher of GCSE Physics.
(In case you haven't worked it out, I'm very interested in Physics )

[stefan einz]

So, not only are you not yet 17 but happy to engage in conversation, using perfect English, on a 'site about a very specific discipline with others who are mainly much older than you but now you reveal that you are deaf.
I doff my hat to you, you'll go far in life, whatever you decide to do.

Well, thanks!
Well, after finishing my GCSEs I intend to do my A-levels (Physics, Chemistry, Maths and Further Maths) then progress into a Physics course at university and hopefully get a PhD then become a lecturer in a university, or a teacher of GCSE Physics.
(In case you haven't worked it out, I'm very interested in Physics )

Good choices! I did the same A-levels, and then read Physics (a long time ago now!).

[WhoseGeneration]

So, not only are you not yet 17 but happy to engage in conversation, using perfect English, on a 'site about a very specific discipline with others who are mainly much older than you but now you reveal that you are deaf.
I doff my hat to you, you'll go far in life, whatever you decide to do.

Well, thanks!
Well, after finishing my GCSEs I intend to do my A-levels (Physics, Chemistry, Maths and Further Maths) then progress into a Physics course at university and hopefully get a PhD then become a lecturer in a university, or a teacher of GCSE Physics.
(In case you haven't worked it out, I'm very interested in Physics )

My late father in law was a physicist, obtained his PhD from Cambridge, Cavendish, when Rutherford was still around.
It's continued in my wife's family, nephew who is also one and a world expert in composites, his wife too,
who teaches aerodynamics at a university.
You'll not go wrong persuing this path.
Unless you get sidetracked into the City with the allure of money.

[stefan einz]

One of the interesting things I am noting is that the car can recharge itself on the move far more quickly than via the mains. That obviously speaks to the limitations of charging the car up at home, using an electrical system with limited capacity.

It takes around 45 minutes of steady driving to bring the charge up from around 15% (which is about as low as the car lets the battery get) up to fully charged. That's pretty good, I think.

Still, that's nowhere near as quick as the Porsche 918 Spyder. I recall that adding about 40% charge within one 5 km lap of the circuit near Seville. Something to do I guess with the 600hp from the petrol engine, and presumably higher capacity batteries that can absorb power more quickly.

Cheers

[TheInsanity1234]

My late father in law was a physicist, obtained his PhD from Cambridge, Cavendish, when Rutherford was still around.
It's continued in my wife's family, nephew who is also one and a world expert in composites, his wife too,
who teaches aerodynamics at a university.
You'll not go wrong persuing this path.
Unless you get sidetracked into the City with the allure of money.

Heh, don't you worry, I'm only in it because of the allure of being able to answer questions that has plagued mankind for generations. (Though a lot of money would be a lovely bonus, since I covet a Range Rover! )

Good choices! I did the same A-levels, and then read Physics (a long time ago now!).

Seems that there are far more academics in the older generations than there are now.
One suspects it has something to do with the increasing numbers of people picking easy topics such as media studies and photography

Anyway, back to the topic!
I've often noticed that there are people who buy hybrid cars that offer mpg figures that are fantastic, and yet under normal driving conditions, they struggle to return mpg figures that would match that of a Golf diesel.
I wonder if this is because the hybrids are marketed as being able to offer higher figures with no difference in your driving style, when in actual fact, you have to change your driving style to exploit the full efficiency of such systems?