OT Hybrid Car Efficiency

Hi all
Wandering round the estate (west of Hull (city of culture)), I notice more of these electric-petrol hybrids appearing.
Do any members of the group run these and, if so, have they any idea on real world efficiency/economy figures? Is an electric drive inherently more efficient than an i c engine? Does regenerative braking make a serious contribution to energy saving?
I suppose it is unlikely that anyone will run a specific make and model of petrol car then swap this for an identical spec hybrid version. But I guess this would be the closest comparison possible - given that it would probably be driven by the same person in the same way on the same roads.
Phil
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We got an Auris Hybrid about 6 months ago. I'm keeping a spreadsheet of fuel purchased vs. miles driven and charting (a) mileage between fillups, (b) average mileage over last five fillups, and (c) average mileage since purchase.
Latest values (after about 4200 miles): (a) 59mpg (b) 58mpg (c) 55mpg.
It does seem to mean that if you happen to do a period of start/stop, consumption does not shoot up as it would without a battery. Consumption so far is somewhat better than the diesel C4 we had before, and emissions should be better as there is less carbon in a litre of petrol than a litre of diesel.

One for car experts.

This car has a screen where a bar chart shows consumption over the last 15 minutes in 1 minute intervals. It also shows, in symbols, how much energy has been saved by regeneration during each one minute. For us, from home into Canterbury, it seems to gather about 200Wh - we are up highish and its downhill all the way.
Now: a litre of fuel contains about 10kWh. If a petrol engine runs at an efficient point, I'm guessing that's about 40% efficiency. Thus, the litre contains about 4kWh of useful energy. So I have to make 20 such journeys to save a litre of fuel. Unfortunately it doesn't seem possible to get the car aggregate those numbers over some period (such as between fillups), but I may over a fillup period save mebbe a couple of litres that would otherwise be wasted. That's about a 5% saving in my case. That just shows up as improved fuel consumption.
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On 10/06/2017 19:37, Tim Streater wrote:

Back in the 70's, Autocar used to cover car rallies where the main aim was use the least amount of fuel.
Even driving cars of that era, astonishing MPG was being attained which must be down to very careful driving.
I suspect todays hybrids just superimpose the action of a careful driver onto a normal driver to achieve the same sort of economy.
In stop/start slow traffic a hybrid must have a massive advantage while there is stored energy available, whereas a gentle cross country run would show less advantage.
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Yes, there's a certain amount of driver training - the displays make it like a video game, where you're aiming to get the high score (mpg).
However that's not bad as such: if you drive it like an F1 car you'll likely get terrible mpg - just like an F1 car. So a bit of training isn't a bad thing. Some hybrids (eg Prius) are very conservatively built, so won't enter the WRC anytime soon, while others are sportier - but if you drive one sportily then expect to pay for it.
But there's still enough advantages to make it worthwhile: you probably won't be driving around town sportily anyway, and it can still make efficiency savings if you do.

Indeed. Though driving at 55 rather than 70 shows a marked advantage. (I was on the motorway the other day stuck behind a crane doing 40 and it kicked into battery-only mode - so even then it can help)
To answe the OP's questions:

I haev a 10 year old Gen2 Prius, which are getting cheap on the secondhamd market now. I'm getting about 58mpg on the display, town or motorway. I think the display over-reads by about 3mpg, but haven't done enough to properly calibrate it.
Maybe I should try a tank's-worth of thrashing it, just to see how bad I can get the average ;-)

Yes: The battery is used at times when the IC would be inefficient The battery can provide bursts of pwoer, so the IC engine can be sized smaller and operate in a more efficient region - eg the Prius is 1.5l for a large-ish car that might typically be a 2l petrol. The gearbox is simplified, reducing losses over a typical automatic It's possible to drive entirely on electric, if you aren't going far enough to be worth warming up the engine.
Additionally there are some IC engine energy saving tricks, eg putting the engine oil in a Thermos flask to keep it warm when stopped. I think they gave up on that in future models because it wasn't worth it.

I typically get 50-100Wh in 5 minutes of town driving, or decelerating from 70 to a stop at the lights at the top of a motorway ramp. That's enough to go 1/8 - 1/4 mile. So not massive, but it helps. It also means almost never having to change brake pads or discs.
Theo
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Theo wrote:

But you can play that game (keep my instantaneous mpg above my average mpg) with a conventional car too ... of course it becomes impossible to improve eventually.
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Mine has an eco mode and a power mode as well as just so-called "normal". It's all drive-by-wire anyway, the gas pedal is connected to the computer, nothing else. I'm usually in power mode, but that does not mean F1 driving, just I'd like be able to crank the speed up if required.

Mine won't do battery mode above about 25. But going Canterbury to Chorley the other week, I got about 65mpg on that tankful.
Oddly enough the engine in mine is 1.8l for some reason.
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On Saturday, 10 June 2017 21:57:41 UTC+1, Theo wrote:

A straight diesel gets better. Hybrids seemed like a good idea, but they're not getting better mpg, which is the whole point of them.
NT
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snipped-for-privacy@gmail.com laid this down on his screen :

My 2L straight diesel in a big heavy car regularly manages 50mpg solo. I once managed over 60mpg on a single run to and from the coast. I don't use it for town work, only open road and for towing. In towns I use an hybrid, called a modern bus :D
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snipped-for-privacy@gmail.com wrote:

If all you're going to do is 70mph cruising, they're equal in mpg to a diesel (though the other advantages like lower maintenance still stand).
The difference is that the diesel is much worse when driven slower, while the hybrid has a pretty much constant mpg across the range. So if you drive on the motorway when it's congested, it does a lot better. Or you do much town driving - there's a good reason a lot of taxis have switched to hybrids.
Theo
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On Sunday, 11 June 2017 09:15:49 UTC+1, Theo wrote:

I get 66-70 in a plain diesel estate from all driving combined. What hybrid does that?
NT
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On 11/06/2017 10:38, snipped-for-privacy@gmail.com wrote:

Which one?
Look it up on here <https://www.honestjohn.co.uk/realmpg/ , and compare typical driver's results with other cars. You may be an unusually economical driver. The Prius, BTW, doesn't do as well as the book figures.
My son had an Astra diesel until recently, when he switched to a Mazda 3 petrol.
Which is using less fuel.
It's a lot nicer to drive too!
Andy
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On Sunday, 11 June 2017 21:22:31 UTC+1, Vir Campestris wrote:

I am. Official figure is 60mpg iirc.

Hybrids sound good on paper, but for whatever reason they just aren't delivering the mpg to warrant their existence. If they lived upto the hype they ought to be doing over 70mpg.
NT
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As I said, they do work very well in cities - heavy stop start traffic. It's for a very good reason many city buses are now hybrids. There has to be an advantage to make the extra cost worthwhile.
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On 11 Jun 2017 09:15:46 +0100 (BST), Theo

Yes, low / zero road tax and exempt the congestion charge. ;-)
I guess if you are driving for your living, all that is very important.
But re road tax ... whist I can see it an incentive to some (those who can't afford to pay whatever the cost ... or need otherwise (like tradesmen etc)), if the point of road tax is to pay for using (and maintaining) the roads, does that mean like FIT, the rest of us are paying more just because our income / lifestyles mean we can't use or afford such?
Like, I often tow stuff and am not sure how many EV's or Hybrids can have a tow bar?
And what when we are all driving them?
Cheers, T i m
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Dunno about now, but the Lexus hybrid Chelsea Tractor is very very popular, but couldn't tow anything useful. Unlike a Range Rover. You'd have thought being able to tow a pony box mandatory.
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On Sun, 11 Jun 2017 13:55:33 +0100, "Dave Plowman (News)"

Quite. ;-)
About the only std car I'm aware of that isn't approved for a towbar is a (1.3) Ka (so potentially also the Fiat 500)?
Daughter has a towbar on her 1.2 16V Corsa and it tows a small camping / goods trailer with no issue. ;-)
Cheers, T i m
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On 11/06/2017 08:35, snipped-for-privacy@gmail.com wrote:

The point of them is to get into a lower tax bracket and to avoid the congestion charge.
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Theo wrote:

Round here the second-hand one mainly seem to become taxis, I don't know if they survive lunar mileage as well as, or better than, the usual favourites?
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You do have to pick through the dross. However there isn't a whole lot to go wrong. I've seen listings for secondhand ones with 300-400K miles on them and they still go. Bear in mind that the engine only runs when it feels the need, so it's very easy on it.
In the >150K range, basically you should expect to budget for a new high voltage battery (GBP950) - a bit like doing the DPF on a diesel. Around then you tend to hit maintenance things you'd have earlier on another car: pads/discs, spark plugs, transmission oil, coolant (radiator and inverter), 12V battery, tyres, AC regas. Almost all of those are things Toyota offers for fixed prices (<GBP200 mostly). The drive itself is basically zero-maintenance.
Like any used car, finding one that's been treated well helps - not the one I viewed that had no oil in it and emitted black smoke. I don't think there's an issue with a well-kept high-miler, it's the one that's been flogged is the problem.
I managed to avoid a couple of turkeys by reading the codes when I went to view - when the car says 'replace HV battery now' that's probably not one you want to be buying unless that's already priced in. Also a lot of dealers keep them on the forecourt with a flat 12V battery - while you can jump start them, running on a low aux supply tends to confuse the electronics which isn't a good idea when you want to see if everything works.
Basically they take high miles well, they just don't like being unmaintained.
Theo
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Running on LPG, if that makes any difference.
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