Author Topic: Warming up.  (Read 1396 times)

Jocko

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Warming up.
« on: September 28, 2019, 03:36:49 PM »
We all know that it takes time for a cold engine to warm up, and even longer for the transmission to get up to temperature. This is worst in the winter, but even in the summer can have a marked effect.
Because I have the ScanGauge fitted I get loads of instantaneous data, and what I have noticed recently is no matter how mpg conscious I am, I cannot get the numbers up, when driving on urban roads, until at least 4 miles have been completed. I find it a lot easier to get good "cold" mpg figures around town than on the open road. On the open road there is less scope for squeezing out a few extra mpg. If my regular run was 4 miles of urban roads in the morning, then 4 miles back again at the end of the day, I would be toiling to better 36 mpg average.
So the numbers you get are as much to do with the type of miles as the style of driving. The bulk of my driving at present is 36 miles of urban roads, then 36 back, with minimum cooling time in between. Hence my current excellent numbers.

John Ratsey

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Re: Warming up.
« Reply #1 on: September 30, 2019, 03:17:41 PM »
I concur with your observations - short trips in cold weather wreak havoc with the mpg while cool weather has a lesser effect. This is very obvious on my HR-V as the trip mpg is one of the display options on the touchscreen thingie snd in very cold weather I think it's around 10 miles before everything has warmed up. After any cold start I try to keep the heating turned off for the first few minutes of a journey to avoid the heater sucking the warmth out of the engine coolant.   

If it were more accessible, I would blank off most of the radiator grille during the winter months to reduce the inflow of cold air into the engine compartment but I can't get my hands in there (unlike my old Austin A35 which got this treatment).

Manufacturers have had no incentive to address this problem while the standard fuel efficiency tests were based on a warmed-up engine. However, the "real life" test cycle helps to encourage manufacturers to add some tweaks to help get the engine warmed up faster. I understand that the new version of the CR-V has some form of thermostatic radiator blinds and I recall reading that the Kia Niro uses, when appropriate, heat from the exhaust to warm up the engine coolant.

One advantage of EVs is that, bar the cold lubricants, they don't suffer from the cold in the same way as infernal combustion engines. And, if the vehicle knows what time a journey is starting then it should be possible to use a bit of power to do some pre-warming, particularly if the vehicle is plugged in.
2022 HR-V Elegance, previously 2020 Jazz Crosstar

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