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Discussion Starter · #1 ·
Hi,

I have had a second-hand 2017 Ioniq Hybrid for six months. Initially it was great on economy (doing around 65 mpg). It has now dropped to around 40mpg doing the same journeys since mid-November.

The battery is charging fine while driving but the car is very very reluctant to kick into EV mode even when cruising. The charge is over the 2/3 mark and I can be cruising with barely anything on the accelerator and it just won’t kick into EV.

Any help greatly appreciated! What is going on?
 

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Have you got the AC on ? What's the outside temperature ?
 

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If you turn off the climate control, does that cause it to switch to EV mode more easily?
 

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Discussion Starter · #5 ·
If you turn off the climate control, does that cause it to switch to EV mode more easily?
I will check more carefully the next time I’m driving but I did think to try it one day and my inclination was that it made no difference. If it helped it was very minimal.

I had expected a drop in economy over winter but not to the tune of 25mpg. I’m sure there must be something bigger at play but nothing is showing up and there haven’t been any changes otherwiSe...
 

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Heater on at the 22 Celsius and outside temp around 5 or 6 Celsius
That may be part of the answer . I very rarely have the heating that high , maybe 19 or 20 tops . I generally have the heating off and use the heated seats and maybe steering wheel . Also I put the heating to low if the windscreen needs de-misting and then tend to turn on AC and turn it up when I hit a hill climb ( when I know ICE is unavoidable ) . It should run in EV OK when you hit a flatter surface then . One thing to remember is that when in EV mode , the ICE cools very quickly so , if the AC is set to 22 , it while kick in again . Of course a lot depends on the terrain :)
 

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Discussion Starter · #7 ·
Thanks @chunga68 – I will try as you say. Would you expect the ICE to cool so rapidly in 6 degree Celsius that it wouldn’t want to use EV. Seems that it shouldn’t be cold enough to have such a drastic impact...
 

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Thanks @chunga68 – I will try as you say. Would you expect the ICE to cool so rapidly in 6 degree Celsius that it wouldn’t want to use EV. Seems that it shouldn’t be cold enough to have such a drastic impact...
The normal running temperature of the ICE is around 90 degrees so it will cool pretty quickly if not being used in EV mode . Winter will affect your mpg , though it shouldn't be 25 mpg . The other thing that will impact your mpg is many short trips . Monday and Tuesday , I did two 50 mile round trips one came back at 68.7 mpg the other at 67.5 .The outside temp was 0 to 2 C . The week before I did some short round trips ( 3 to 6 miles ) which often came back around 50 mpg
 

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As an after thought , have you checked your tyre pressures ?. They should be 36 psi when cold .
 

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"Cold" is at 20c as I understand it. So at 5c they should be lower than that, right?

I understood from googling that the rule of thumb is 0.1bar or around 1.5psi per 10c change. So at 0c, cold tyre pressure should be 36psi minus 3psi.
 

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Discussion Starter · #11 ·
Thanks both — tyre pressure is fine (about 34 when cold, rising to 35/36 when warm from driving)...
 

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Thanks both — tyre pressure is fine (about 34 when cold, rising to 35/36 when warm from driving)...
Tyre pressure should be 36 when cold rising to 38 to 40 when warm ( depending on outside temperature ) . I normally set mine to about 38 in winter at a warmer part of the day to allow for the overnight temperature/ pressure drop . I would put some air in if I were you :)
 

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"Cold" is at 20c as I understand it. So at 5c they should be lower than that, right?

I understood from googling that the rule of thumb is 0.1bar or around 1.5psi per 10c change. So at 0c, cold tyre pressure should be 36psi minus 3psi.
Not sure to be honest . But in cold weather and short trips the pressure will almost always be low which loses mpg .
Lower temperatures mean lower tire pressure, so be prepared to inflate your tires more often during the cold weather months.
Cars typically require a tire pressure of 30 to 35 psi (pounds of force per square inch). The recommended psi for your car is the ideal tire pressure year-round; there aren’t different numbers for summer or winter. The temperature does affect tire pressure, however. So when the temperature drops, you might be inflating your tires more often to maintain ideal pressure.
 

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According to bushtyres.co.uk

"If the pressure is measured at +20°C (garage temperature in the morning), tyres should be inflated at recommended manufacturer's tyre pressure (for example, 2.0 bar). If the temperature drops to 0°C, pressure of 1.8 bar should not be increased.

If the outside temperature rose to +40°C pressure of 2.2 bar should not be lowered."

This doesn't sit right with me. Since pressure is all about the contact surface area being right, shouldn't tyres be at the right pressure for the ambient and expected operating temperature? I'd have thought that operating temperature would bear some relationship to the ambient temperature, thus we shouldn't we compensate for ambient temperature accordingly with pressure? Add a little in winter and take a little in summer if the rule of thumb suggests so?

This report from Toyota suggests we should:

https://static.nhtsa.gov/odi/tsbs/2014/MC-10133726-9999.pdf
 

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RE ; Bush Tyres ,I'd like to know what garage temperature is at 20C at 7.30 a.m. in the UK :D
 

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Since pressure is all about the contact surface area being right, shouldn't tyres be at the right pressure for the ambient and expected operating temperature?
Yes. 36 psi when cold really means 36 psi at ambient. If the tires held air perfectly you'd be letting some out for summer and adding some back in for winter. Since it always leaks out a bit though, in reality you're just adding it more often through the fall and into winter.
 
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All of the things mentioned will have a bearing on the MPG, but it would not mean a 25 mpg drop. I would consider having the Battery Management System checked. The BMS is the brains of any battery powered electric vehicle.
 

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The Hybrid operating system prioritizes passenger comfort over fuel economy, and that means it will not let the coolant temp fall below the level necessary to provide sufficient cabin heat. That means that the engine will run more to keep the coolant warm. You can see that if you display the the engine coolant temp gauge (bar-graph) on the dash while driving on a cold day, the coolant temp drops whenever the engine stops (EV mode). If you want to optimize winter fuel economy, don't set the interior temp any higher than you really want, and keep the fan speed as low as you can be comfortable with.
 
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