MPG v. speed

[AndrueC]

My Dad's funeral was today so I had to drive 190 miles to North Wales in the morning then come back down this afternoon. Going up I pretty much stuck to 60 mph and cruise control. It took 3.5 hours and the car displayed 65.2 mpg, I filled up on arrival. Coming back I pegged it, driving at speeds of up to 90 mph as traffic allowed. The journey took 3 hours and the car is currently showing 53.2 mpg.

Make of that what you will 🙂

Oh and I can confirm that the 1.8 Corolla is more than capable of fighting to maintain 90 mph along with the other idiots 🙂

The only glitch was that coming back along the M54 I failed to correctly navigate to the M6 toll and ended up getting back onto the M6 thus wasting some petrol in a pointless diversion. I don't understand why M6T isn't sign posted on the M54. Or for that matter why there still isn't a direct connection.

[FROSTYBALLS]

Probably something to do with the M6 Toll being a Private Finance Initiative and the terms of the contract.

[Timmon]

Sorry for your Loss Andrue. 

[AndrueC]

8 minutes ago, Timmon said:

Sorry for your Loss Andrue. 

Thank you. It wasn't unexpected. He'd been fighting a second bout of cancer so we could see the writing on the wall. But it would have been better if we could have stayed overnight. I suppose we have to be pleased that the Corolla allows you to drive 400 miles in one day without feeling fatigued.

[Timmon]

16 minutes ago, AndrueC said:

Thank you. It wasn't unexpected. He'd been fighting a second bout of cancer so we could see the writing on the wall. But it would have been better if we could have stayed overnight. I suppose we have to be pleased that the Corolla allows you to drive 400 miles in one day without feeling fatigued.

Oh, I'm sorry, the dreaded C.

Yes, It is remarkable the difference the Corolla makes, compared to a manual.  I bought the Corolla because I needed to get to Devon with no stress, at a moment's notice. Although my SAAB never let me down, I was conscious of it's age. My Brother was in and out of Hospital with Prostate Cancer, and I was part time carer, and also hoped he would recover enough to take him for a break. Sadly he died last year, so I was grateful to drive back and forth to Devon making all the preparations and dealing with his affairs, without feeling exhausted.

I've not done a 400 mile in the Corolla, In the SAAB I used to drive to Newcastle, do a days work and drive back in a day, which was over 500, and that could be fairly knackering! I could have done with all the technology the Corolla has in those days!

[MarcusWatson]

It’s shocking how much difference the extra speed makes.

I am currently doing my first ever “pump to pump” test on my 1.8. However, I am wondering why, as I don’t think it’s an accurate way of measuring consumption when using the “click to click” method (that most people arguing in the Autocar comment section seem to reference, in order to prove beyond doubt that their wildly excessive mpg claims are true and that their adversaries claims are clearly codswallop). 

This method relies on the idea that you are able to fill the tank to exactly the same level twice.  However, the fuel pump doesn’t make this easy.  I’ve noticed you can get quite a bit more fuel into the car if you raise the nozzle in the tank, which you can do by pushing down on the handle and/or rotating it.  If the car is parked at a different tilt this would also make a difference.  Even worse if you fill up at different pumps the nozzle might be a different length.  Plus, is the auto stop mechanism actually that accurate in itself?  It will at least have a latency and so if a pump flows faster then more fuel gets dispensed before the mechanism reacts.  I also reckon pumps would vary in rate due to factors such as how full storage tanks are, whether other pumps are in use, whether the station owner has adjusted the flow rate dial for some reason and maybe even ambient temperature.

Also I don’t trust the odometer, it’ll be inaccurate due to calibration, wheel slip, tyre pressure and wear.

My point is that you could easily get a significant difference and as such the click-to-click method (which I’m currently doing) is pointless and probably we might as well just go off the trip computer (as we are doing) and so everything I’m saying is pointless.

Thank you.

[AndrueC]

I normally use the click to click method and from the same pump. I reckon if the same person fills the car using their preferred technique the difference will be relatively minor. But when filling at a different pump it's worth noting how much difference rounding up can make. My own experience is that the dash is usually about 10% optimistic but there was one notable occasion shortly after I got the car when it seemed to be 30% optimistic. Not had that happen again.

Oh and just to be clear keeping up with the other 90mph idiots in a 1.8 does require that you floor the accelerator when a gap opens up. But I've always taken the view that the pedal travel is there for a reason, as is the red line. I've paid for both and am happy to use them when required. The idea of 'being able to keep up while barely tickling the accelerator pedal' is alien to me. Tickling the accelerator pedal is for efficient driving. When you want to move..floor the *censored* 🙂

[TonyHSD]

Sorry for your loss Andrue,  Speed vs consumption applies to all vehicles and all types of power, the idiots who drive like that all the times  also pay the price for that but they doesn’t care and also doesn’t care about the vehicle they drive as driving flat out often or for extended period of time significantly decrease the life of the car and all components, engine, transmission, brakes, suspension everything is overloaded. For the petrol pumps I agree to some extent, however if you follow some important steps you can get very close results to the actual consumption, all mentioned already. Since these cars are drive by wire, choosing between different driving modes makes a huge difference in how the car fees , performance pretty much stays the same. , driving faster in power mode release some pressure of the driver, it’s same like doing a full turn with car with power steering or without power steering rack, old school where muscles are needed to turn the wheel. Toyota 1.8 hybrids are capable of “keep up with traffic “ madness however they are designed to make you drive otherwise, not slow but relaxed and smooth ride like a pro driver. 👍

[frizzbee30]

 Absolutely!!

[AndrueC]

Filled up today (might as well start the lock down with a full tank) and the pump to pump figure was 50.5 which is pretty good for a car being driven by an (almost) raving mad man 🙂

Whether I'll need a full tank of fuel for what's left of this year is another matter but speaking as a golfer it seems like we're not taking this latest decision lying down. Mr Johnson is going to have to explain himself 🙂

[HybridLover]

what's the click to click method?

[HybridLover]

I calculate my MPG by current mileage when fuelling minus mileage at last re fuel / amount of fuel put in.

[AndrueC]

9 hours ago, HybridLover said:

what's the click to click method?

It just means filling the tank until the pump clicks off each time. Put petrol in, 'click', drive, put petrol in, 'click' filled again. 'Click to click' :)

[frizzbee30]

I'm a bit bemused,  as to why the onboard calculated figure isn't being used?

 

EPROM profiling is very exact, and the system metering is spot on, so the car figures should be fairly close.

However,  pump clicks have soo many variables,  even with a full tank to tank, add in the allowed weights and measures variance.

 

Just seems odd, but perhaps its my science/frontline healthcare background, where variance and control are critical. 😊

[AndrueC]

I read once that it's not that easy to measure but I confess I don't know why. From what I remember most manufacturers use the frequency and duration of injector pulses to determine fuel consumption and that has issues:

https://www.caranddriver.com/news/a15369613/why-your-trip-computer-isnt-giving-accurate-mpg-readings-and-how-to-fix-it/

"Mark Allen, GM’s director of global energy, mass, and aerodynamics, says some inaccuracy is unavoidable. “The density of fuel varies. We have no way to measure it. Mobil might be different than Shell. Summer gas to winter gas could be a big difference.” And then there are vapor-recovery systems. With modern cars’ sealed fuel tanks, gasoline vapor accumulated in the tank is absorbed by a charcoal-filled canister. Periodically, this canister is purged by the engine. “If the weather is hot, you generate lots of purge,” says Allen. “This unmetered fuel isn’t counted by the trip computer.”"

In my case I can say that the difference is pretty consistent so either my calculation/readings are consistently wrong or the car is and is regardless of what pump I use. Given that both me and the car are relying on the same odometer I'd say it's pretty clear that the car is wrong.