The Sweet Spot on Highway Mileage.

As a owner of Gen2 2005 Prius currently at 205K miles and based in UK. I am not a hypermiling freak , I drive normally albeit a little conservative. I would like to open a discussion on Highway Mileage after I noticed something peculiar.

I have come to realise that the sweet spot for Highway Mileage for this car is at about 55MPH. I noticed it when we had a traffic at Motorway mainatiance where we are to drive at speed of 50MPH for about 5 miles. The speed is mainatianed constant throughout 5 miles and I noticed the MPG I got is surprisingly 65MPG. When I went back to 70MPG it drastically dropped to below 50MPG. I used to always take the right Lane and drive at 75 to 80MPH or even above for maximising fuel efficiency and used to complain on 40MPG it got. From then on I realised the sweet spot and always took the Dual Carraigeways where ever possible to take 50MPH route instead.
I am not complaining about city mileage as it is sensible enough to know that Prius and any hybrid always saves you great on the city. So I am trying not to discuss City Mileage here.

Has anyone ever tried doing it with their Prius . I am curious to know the more powerful 1.8L on Gen 3 or above would give you a higher sweet spot probably at 65MPH.

And of course the new Corolla Hybrids with number of option from 1.2L turbo, 1.8L and 2.0L. And here's my little theory - since Corolla being lighter than Prius , the same 1.8L can push the sweet spot to the UK standard 70MPH Motorway. And for some of us who tend to take right Lane to cruise at 80MPH or above , the Corolla 2.0L might save you better at that speed.

And as we can imagine the Turbos always gets you more power on less fuel, the new Corolla Hybrids has the option too, the 1.2L turbo Hybrid. As funny as it may sound I was playing with this idea in my head few months ago , and Toyota has all three options now in their Corolla Hybrids. Anyone with the new Corolla Hybrids please exercise on your data. I myself am longing to get the 1.2 L just to drive this curiosity of mine.

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Except in my Gen 2 Prius: above the 55MPH, the MPG tends to go up drastically to below 50MPH (@70 MPH) and to 40MPG (@ 80MPH). The Chart sort of will look like a upward facing paraboloid instead.


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Sorry I actually meant when I get to the 70MPH Motorway speed, the MPG drops down to below 50MPG. I have never gotten 70MPG.

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And yes I am referring to the imperial MPG.
My measurent were taken on the basis of Prius dash screen information.
And what I did was reset. I resetted before I drove 5 miles @ 50MPH which gave me 65 MPG. Then I reset it again to measure on about 10 miles @ 70MPH which gave 49.** MPG.




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Thanks. I appreciate it.

 

You have the latest Prius Prime and equipped with a larger engine capacity 1.8L as compared to mine which is a 1.5L.
And Prius Prime has a larger electric motors that will assist even at higher speed. With mine, the electric motor is pretty much idle after 40MPH.
Also are you mentioning your average MPGs combined city and highway. I was just focusing on the Highway mileage , constant 70MPH over 10+miles. Next time when you get into interstate highways or motorways try resetting the dash and read what it says at the end of the 10miles trip.

 

Its been a week my car gave P0016 error. May be the timing chain.
Anyway I am driving it as it is.

Just yesterday drove 5 miles constant @50MPH in Cruise Control Mode and actually got 75 MPG. -- UK. (US- 60MPG).
I was driving alone with no passenger and no luggage. The road was wet with recent heavy rain and temp about 18C(64F).

Just yesterday had to drive very far using the Motorway M4. From Junction 11 - junction 13 had to drive through 50MPH highway mainatiance traffic. Reset the dash, put it on cruise 51MPH , and BAM after 5 miles my mileage was 75MPG.

Then I drove 50miles at motorway @70 MPH cruise , my mileage was 52 MPG(US 43MPG).

I will have timing chain replaced soon. And see how it does again.





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