Hybrid using a lot of petrol

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456 posts

Ultimate Geek

#2939905 8-Jul-2022 23:10

Have definitely noticed that the fuel gauge goes down quicker than my old Honda Accord, but that had a significantly larger tank.
One other thing to potentially check is the 12volt battery.(standard car battery) I have read online that once they start to get old and loose charge the fuel consumption does increase.

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Scott3

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#2939910 9-Jul-2022 00:09

Good to read that the users here have identified the likely issue....

A non linear gauge read out, meaning the gauge drops quickly in the middle of the read out.

As a side note, my lexus RX hybrid has a 65L tank, I don't think It has ever taken more than about 53L in it. Must have about 15L left when the fuel light comes on. And even though I know this, having no further accurate indication of the remaining fuel means the risk / reward of using that reserve is not worthwhile for me. Essentially meaning I am lugging around 10L or so of fuel that is essentially useless to me, significantly cutting the usable range of the car. However this doesn't really materially impact me as fuel stations are common where I drive.

Much prefer the system on the out lander that a family member had, where there was two low fuel alarms, one at 10L and one at 5L

Eva888:

Good to hear from someone else with a similar car. Have you noticed the fuel gauge dropping as you drive also? I’m still unsure if it’s problematic or not. Seems mine is not as efficient as yours as it shows about 15km/L even with purposely not using heaters and careful driving. Not enjoying driving this way but trying to rule out a heavy gas foot causing it.

Was nervous to tinker with the settings in case I scrubbed the information but now have photos for comparison. I need to figure out how to reset all the counters and then top it up with gas and begin from there to get an accurate reading before I take it in to be checked. Also want to photograph the gauge each time I use the car to record the drop.

Don't worry about the heater use.

Basically any (non plug in) car, when up to temperature and diving, produces a large amount of waste heat. Any heat that is not used to heat the cabin, gets dumped outside via the main radiator.

Essentially means the only cost to run the heater is the power to turn the fan, which might be 100 watts or so, pretty negligable in the scheme of running the car.

Seat heater's are also fairly negligible (80-200 Watts each), but if you want to optimize, once you car is up to temperature, the main heater will have a lesser impact on fuel economy.

While the car is warming up, use of the heater may have a small impact. Any heat sucked off the engine, means it the engine is slower to reach it's most efficient temperature. And on my RX hybrid, if I set a high cabin temp, the hybrid system will respond by running the engine even if it would normally be off.

But I just leave my temp set point at about 23 or so, and in auto. Car knows not to bother running the fan for the first couple of minute's, so it seems to be smart enough to look after itself.

Obvious time when using the heater adds a lot to fuel consumption is if you sit for 10 or so mins in a parked car with the heater running. At some point the car will fire up the engine, simply to produce waste heat to keep the heater running.

Toyota / lexus hybrids have a few tricks to speed warming. Mine has a thermos flask that it will pump hot coolant into after shutdown, so it can pump it back into then engine when you open the drivers door, on anticipation of the next start (can hear the pump if it is very quiet outside). Assume the CT200h has the same.

Seems like the CT200h has the ability to scavenge heat from the exhaust, and automatically run the seat heater if it feels that is more efficient than running the main heater (not enough heat coming from the engine)

https://mag.lexus.co.uk/how-the-lexus-ct-200h-defends-you-against-the-cold/

And don't pay to much attention to on screen fuel economy displays, while useful to see what impacts fuel consumption, they have a reputation for being inaccurate (they don't directly measure fuel consumption). The test where you full the tank, and see how far it takes you, then calculate economy based on your next fill with gain you the most accurate information.

gzt

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#2939915 9-Jul-2022 07:04

Eva888: Seems mine is not as efficient as yours as it shows about 15km/L

Personally I suggest resetting the counters. This way you'll get an average for your actual use. Fresh of the boat the average tends to look horrible because typically it's been reset a few times and used in loading yards jump started etc. As I've said before it's a bit meaningless until you've used a few tanks.

gzt

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#2939917 9-Jul-2022 07:29

Scott3: And don't pay to much attention to on screen fuel economy displays, while useful to see what impacts fuel consumption, they have a reputation for being inaccurate (they don't directly measure fuel consumption).

Just to be clear, in my experience calculating using petrol receipts after a reset the average on the display is 100% accurate and matches fuel used exactly. Scott3 is talking about the instantaneous graphs and instantaneous 'now' figure in that para for momentary consumption. I hope that helps.

Dingbatt

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#2939918 9-Jul-2022 07:39

My experience with many years of driving a Toyota Hybrid (Camry) is that multiple really short journeys (less than 5km) kills the efficiency. The engine warms up on first start, then under urban driving it runs until the battery is depleted and then the ICE starts to recharge and provide motive power. If the run is short enough, then the battery doesn’t fully recharge and the next time you start off, the electric run is even shorter before the ICE cuts in.

Day in, day out I achieved 5.2l/100km (about 19km/l) in my Camry. Since the CT200 is based on the Corolla Hybrid, I’d be really surprised if it was worse than my Camry was.

Edit: Because of the design of modern fuel tanks, the fill-run-fill method to determine efficiency is only good for a gross check. The baffles and shape of the top of the tank can affect how ‘full’ the tank actually is before the fuel comes up the spout. Likewise the density and temperature on the day can affect when the bowser shuts off.

“We’ve arranged a society based on science and technology, in which nobody understands anything about science technology. Carl Sagan 1996

Batman

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#2939919 9-Jul-2022 07:44

could be wrong, i thought modern plug in hybrids you can set it to never use engine?

Dingbatt

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#2939920 9-Jul-2022 07:47

Batman:

could be wrong, i thought modern plug in hybrids you can set it to never use engine?

AFAIK you can set an ‘EV Mode’, but if the car needs the ICE it will override it. (Noting the OP’s vehicle isn’t a plug-in).

“We’ve arranged a society based on science and technology, in which nobody understands anything about science technology. Carl Sagan 1996

Eva888

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#2939950 9-Jul-2022 10:20

Thanks everyone for all the very detailed and helpful input. I really don't fully understand how hybrids work. It is NZ new so screens are English.

The owner was very upfront, selling as he was terminal. We had developed a nice rapport over negotiations so it was difficult to accept it was a lemon. Would have bought a Prius as a step up from Aqua and with lots of boot room, but daughter insisted that strangers would be hopping in thinking I was an Uber. Let’s see how she feels next time she returns from an overseas trip and her ample luggage doesn’t fit in my now tiny boot.

Just measured, most of my trips are about 6km there and 6km back, didn’t realise that was a bad thing for fuel economy as thought that hybrids were economical city cars, but once I reset it and fill, will head up the coast and see what the numbers are. It makes sense that the gauge would go down faster the smaller the tank, however the little Aqua ran for days with the needle on full.

Not living on the flat means each trip is returning up a hill. Eco is sluggish. Is it best to put it in Sport or Normal going uphill?

Will also get the normal battery checked as suggested. Is this something I can do at home with the right tool? Am happy to buy a meter if it’s simple to use.

Scott3

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#2939953 9-Jul-2022 10:34

Batman:

could be wrong, i thought modern plug in hybrids you can set it to never use engine?

None of the car's under discussion are plug in hybrids.

My hybrid doesn't have an EV mode button, but more modern Toyota / Lexus hybrids do. Note that with most of the Toyota / Lexus hybrids their are drive train limitations when running in electric, If you call for a lot of power, or to accelerate when at higher speed, the engine needs to start to accommodate this. I assume for safety, the Toyota / Lexus cars will simply abandon EV mode if you floor it, but have never tried myself.

Anyway, given the car's arn't plug in's, EV mode is more about running in Emissions / noise sensitive area's (say covered carparks), all that energy has to come from the engine / fuel at some point anyway, it is just deferring that.

On plug in hybrids, most run on the philosophy to run on electric, until the battery reaches some lower limit, then will switch across to to a hybrid operation mode, aiming to keep the battery within a few percentage points of the lower limit. But there are lots of reasons that the car's start their engines despite having lots of charge in the battery:

Aggressive acceleration. Many PHEV's will fire up the engine to chip in with overall power. This is how the likes of the Rav4 Prime is something like the 3rd quickest car in toyota's lineup, doing 0-100 in 5.9 sec. Some PHEV's do not do this, like the BMW i3 REX I used to have (125kW output regardless of if the engine was running).
Engine scheduled maintenance run. Good for engines to be run now and then, and for enough fuel to be burnt to avoid the tank going stale. Most phev's will start and run the engine if it hasn't been run for several weeks.
User command - Most Phev's have some kind of Battery hold / save / charge mode. Allows the electric running to be saved for the tail end of the trip, and gives a much larger battery buffer before hitting turtle mode if doing something onerous, like towing up mountains, driving at extremely high speed etc.

Behodar

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#2939954 9-Jul-2022 10:37

Scott3: I assume for safety, the Toyota / Lexus cars will simply abandon EV mode if you floor it, but have never tried myself.

Yep, it emits a little "beep beep" and switches off EV mode, with a message on the display. At least on mine the EV-only mode is intended for driving around a neighbourhood at night and is limited to around 40 km/h (in hybrid mode it can easily exceed this with the engine off, but then there's no guarantee that the engine won't start).

Scott3

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#2939955 9-Jul-2022 10:38

gzt:
Scott3: And don't pay to much attention to on screen fuel economy displays, while useful to see what impacts fuel consumption, they have a reputation for being inaccurate (they don't directly measure fuel consumption).

Just to be clear, in my experience calculating using petrol receipts after a reset the average on the display is 100% accurate and matches fuel used exactly. Scott3 is talking about the instantaneous graphs and instantaneous 'now' figure in that para for momentary consumption. I hope that helps.

It's great that your car's reporting is spot on, but many car's will understate their average L/100km on the dash (so the driver thinks the car is more efficient than it actually is).

Same deal as many car's overstating their speed (km/h). If the car is going slower than the driver think's it is, the car will be quieter, more economical, and give the perception of having better acceleration, compared to a car with an accurate speed read out.

Scott3

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#2939959 9-Jul-2022 11:26

Eva888: Thanks everyone for all the very detailed and helpful input. I really don't fully understand how hybrids work. It is NZ new so screens are English.

The owner was very upfront, selling as he was terminal. We had developed a nice rapport over negotiations so it was difficult to accept it was a lemon. Would have bought a Prius as a step up from Aqua and with lots of boot room, but daughter insisted that strangers would be hopping in thinking I was an Uber. Let’s see how she feels next time she returns from an overseas trip and her ample luggage doesn’t fit in my now tiny boot.

Just measured, most of my trips are about 6km there and 6km back, didn’t realise that was a bad thing for fuel economy as thought that hybrids were economical city cars, but once I reset it and fill, will head up the coast and see what the numbers are. It makes sense that the gauge would go down faster the smaller the tank, however the little Aqua ran for days with the needle on full.

Not living on the flat means each trip is returning up a hill. Eco is sluggish. Is it best to put it in Sport or Normal going uphill?

Will also get the normal battery checked as suggested. Is this something I can do at home with the right tool? Am happy to buy a meter if it’s simple to use.

The beauty of the toyota / lexus hybrids is that you don't need to understand how they work.

Mine doesn't even have modes.

Personally I would just run normal mode all the time. On most car's eco mode largely changes the accelerator map, encouraging slower acceleration, and slower travel in general. The economy win comes from getting the driver to drive slower, which of course they could also do in normal mode if they wanted to drive slower...

Not sure what it does on the CT200h, but on some car's (golf GTi as an example), sport mode will keep engine in it's powerband, so power is available instantly, rather than shifting up for more economical RPM, obviously this would cause a significant increase in fuel consumption. But nice if you want to thrash the car on a track, or through some bends.

Don't worry about the 6km trips. In l/100km terms, yeah the car uses more fuel per km for shorter trips (as a larger proportion is cold running), but in absolute (Liters) terms, the shorter the trip, the better.

As i previously mentioned you car has clever tricks up it's sleeve to warm itself quickly and efficiently.

And, yes, hybrids are great economical city cars, including for short running. Will easily beat non hybrid cars in the same duty. (not as good as a pure EV though, which has no need to warm anything, so basically not impacted by short running).

Regarding the 12v battery, yeah you can buy your own load tester, but heaps of places will test it for you for free (like Beaurepairs), and they will have a better tester than what you would realistically buy. Just type free battery test [city] into google.

Personally I doubt the 12v battery would have much of an impact on economy. Whenever the car is on, the DC-DC converter will basically be powering the 12v loads directly with power from the larger traction battery pack. 12v battery basically exists to power systems like the alarm and remote key, while the car is off, to provide enough power to start the computer which can start the DC-DC converter, and to provide some power for lights etc in an emergency. Engine cranked over by the higher voltage traction pack. As such many hybrids have small 12v batteries. My lexus RX large 6 cylinder SUV, packed with electrical goodies (3x lights for the boot alone, seat heaters, power tailgate opener etc), has the exactly the same size battery as the 1.8L (non hybrid) corolla I used to have. BMW i3 has a battery that looked similar to a motorcycle / ride on lawnmower battery.

On doubting your car purchase, My advice is don't. The CT200h is a very nice car.

Yes it gets the same drive-train as a 3rd gen prius. Yes it is a little heavier and less aerodynamic, so it would be a touch slower, and use a slightly more fuel (only about 0.3L/100km more).

But the acoustic insulation, refinement, interior quality and comfort will be hands down better than a Prius (which in itself is quite a step up from an aqua).

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#2939960 9-Jul-2022 11:26

Eva888:

Just measured, most of my trips are about 6km there and 6km back, didn’t realise that was a bad thing for fuel economy as thought that hybrids were economical city cars

me being a hybrid skeptic actually thought the same as you.

i thought hybrids are only good for short trips

turns out "plug in hybrids are good for short trips" and your hybrid is good for not so short and not so long trips - now i'm even more skeptic!

i have gas and and pure EV, one for short trips one for everything else. i guess it depends on one's needs and commute patterns

Scott3

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#2940027 9-Jul-2022 12:10

Batman:

...

i thought hybrids are only good for short trips

turns out "plug in hybrids are good for short trips" and your hybrid is good for not so short and not so long trips - now i'm even more skeptic!

...

Hybrids will comfortably beat the fuel economy of equivalent non hybrids on both short and long trips (bit will do so by a bigger margin in urban conditions with traffic etc.)

Obviously not as good as an EV, which has no short trip economy penalty, but you get a much longer range. (my household has both a hybrid and an Ev)

Dingbatt

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#2940031 9-Jul-2022 12:22

Maybe I should be clear about my “kills its efficiency” comment about short runs. It will still be good when compared to normal ICE vehicles, just not as efficient as it can be. Once again using my trusty old Camry Hybrid as an example, short runs might result in efficiency as poor as 7l/100km while I could get 4.7l/100km on a long motorway/expressway run. The 3.5l Maxima the Camry replaced was 11l/100km around town and about 7.5 on the open road.

I don’t know what there is to be skeptical about with hybrids, as long as you recognise that all of the energy they use comes from their fuel tank and not some magical supply of fairy dust. And that some very clever engineers have figured out how to achieve that without the owner having to do much other than putting petrol in and keeping it serviced.

“We’ve arranged a society based on science and technology, in which nobody understands anything about science technology. Carl Sagan 1996

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