[chunga68]

The other way to check eco versus sport mode is to use the instantaneous mpg readout selectable to the right of the speedo.

I've done so on the the mountain road in the morning . Sport was marginally heavier on petrol , but I was driving steadily . If I'd floored it , the results would have been worse I should think

 

[bluecar1]

technically there is no difference in the engine power between ECO and SPORT as only the accelerator / gas peddle mapping changes, along with that it is more aggressive charging and electric motor use to make it seem quicker

so I wouldn't expect to see much difference in mpg if driven in a similar way

 

[Fracino]

I think there IS a difference beyond the accelerator mapping: the DCT programming seems to be different to. With a given acceleration at a given speed on a given slope, the DCT will downshift earlier in sport mode than in eco mode. Therefore the average rev is higher in sport mode than in eco mode. Or so it seems: there is no tachometer or gear display in eco mode, so difficult to measure. But the engine sounds quieter in eco mode, which is a basic indication of lower rev.


However higher rev and lower gear do not necessarily translate into much lower fuel economy. The engine must generate extra power at higher rev, but does so more efficiently. Also, thanks to the hybrid system, excess energy generated by high rev may be stored in the traction battery.

 

[bluecar1]

yep there are different mapping of change points on the DCT and steering assistance as well

but I was looking at it purely from an engine power position

 

[yticolev]

However higher rev and lower gear do not necessarily translate into much lower fuel economy. The engine must generate extra power at higher rev, but does so more efficiently. Also, thanks to the hybrid system, excess energy generated by high rev may be stored in the traction battery.

The word "efficient" in English means something different than you think for engine design. It is power that is produced efficiently by the design of the engine which usually entails pushing more fuel into cylinders while keeping the fuel air ratio similar. This can be done by higher compression, or devices that effectively do the same such as turbos and superchargers. The result is higher power per cc cylinder size, not higher fuel efficiency.

Also, thanks to the hybrid system, excess energy generated by high rev may be stored in the traction battery.

This is like coasting versus regeneration. Which is more efficient? Every form of storage has overhead and efficiency losses. Would you idle or race your engine at a stop to recharge the battery? Nor do you want to increase revs going up a hill. Let the car decide on the most efficient gear in Eco.

 

[Fracino]

I meant "engine efficiency" in the sense of Wikipedia English. It may or may not be proper English: I'm not the one to say.


https://en.wikipedia.org/wiki/Engine_efficiency#Gasoline_(petrol)_engines

Engine efficiency peaks in most applications at around 75% of rated engine power, which is also the range of greatest engine torque (e.g. in most modern passenger automobile engines with a redline of about 6,000 RPM, maximum torque is obtained at about 4,500 RPM, and maximum engine power is obtained at about 6,000 RPM).[citation needed] At all other combinations of engine speed and torque, the thermal efficiency is less than this maximum.

 

[Gearbox Paul]

I've read a few comments on this forum saying that is is preferable (to improve fuel economy) to use Sport mode going up hills. It's not clear to me why that is. I drove the car today on the highway at about 100 km/hr. In Eco mode, the car runs in hybrid mode (ICE running) when going up hills. If I switch to Sport to go up the hill, the car is still in hybrid mode. I notice Sport mode drops the DCT from 6th to 5th and the rpms increase accordingly. How does that save fuel ? Can someone please explain ? Thanks.

Thanks for the responses. From your comments, I don't see any compelling evidence that using Sport mode for going up hills improves fuel economy, compared to keeping the car in ECO mode. Which is what I suspected.

 

[droth4]

For any vehicle, the best efficiency occurs by operating the engine at close to Wide-open Throttle at the lowest engine speed that you can get the power the vehicle requires. This varies a bit, depending on how knock-limited the engine is and whether the engine calibration lets it go to a rich mixture at high loads. If you plot an engine's torque capability on the y-axis vs engine speed; the least efficient region to operate in is the lower right-hand corner (light-load and high rpm), and the best efficiency is in the upper-left to upper-center region.

Dave

 

[JBSwiftus]

BSFC. Brake Specific Fuel Consumption is typically best around peak torque. But that doesn't overall mean that the most efficient parameters for a vehicle are at BSFC. Just the engine.

 

[yticolev]

Or in the old days, maximizing mpg by short shifting with an open throttle.

 

[coverman]

Short shifting with an open throttle if using the clutch will cause premature clutch wear on an ICE car. If not using the clutch, by feeling into the next gear is ok if the gearbox is slick enough to accomodate this behaviour. .

 

[yticolev]

Short shifting means shifting early. Open throttle is after shift has occurred. Very different from speed shifting.

 

[malbeck]

Range remaining was 68. Very cheap fuel here in Florida.

Sent from my iPhone using Tapatalk

 

[JBSwiftus]

Driving in a flatter than a pancake state does seem to have its benefits. Also your gas is 50% cheaper than mine!

 

[bluecar1]

i'm jealous just cost me £50 ($63.75) to fill mine yesterday

 

[SEvans]

Short shifting with an open throttle if using the clutch will cause premature clutch wear on an ICE car. If not using the clutch, by feeling into the next gear is ok if the gearbox is slick enough to accomodate this behaviour. .

Yes, but NOT with a DCT.
In practical terms, the gear `following` is already engaged... Up or down. :nerd:

 

[SEvans]

i'm jealous just cost me £50 ($63.75) to fill mine yesterday

I went to Westward Ho! from Southampton last weekend - 150 miles at `not economical` speeds - total cost to return the mileometer to the same mileage as at leaving, give or take a dozen miles?

20 quid - a 300 mile round trip for just £20? Equal to £1.23/ litre or £5.59 gallon = 300 miles or 53.66 UK miles per gallon and this was in cold weather, with rain and (er, officer) no attempt to maximise economy, whilst two-up with luggage... I'm very happy at the fuel economy of the PHEV! One can read about my last A361 run in the summer at less-than-economical speeds: https://www.ioniqforum.com/forum/218-hyundai-ioniq-hybrid/2378-fuel-economy-hybrid-26.html

These are rough figures.
My notional average reduced from 79.9 mpg to 78.4 mpg according to the car readings with NO electricity top ups en route. I'm very 'appy - as Valentino would say...

 

[coverman]

Surely shifting with a DCT involves both of the dual clutches to disengage the gear in use and then engage the next gear.

 

[SEvans]

Surely shifting with a DCT involves both of the dual clutches to disengage the gear in use and then engage the next gear.

No:
https://auto.howstuffworks.com/dual-clutch-transmission.htm

:nerd:

 

[Bermah]

i'm jealous just cost me £50 ($63.75) to fill mine yesterday

Man, this IS expensive. I usually spend $20+ on a fill up. On the flip side, cheap fuel is what makes EV adoption slow in the USA. In my state (New Jersey) with electricity cost of 15 cents per kWh and fuel cost around $2.40 per US gallon, it is only 25% cheaper to drive an Ioniq HEV vs EV. Not too many want to jump on the electric wagon, given the limited range and relative scarcity of public chargers. Myself included. If I move to one of the west coast states I’ll buy an EV immediately.