Which is the most efficient gear for highway driving

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johu
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Which is the most efficient gear for highway driving

Post by johu »

Did a little test:
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Re: Which is the most efficient gear for highway driving

Post by MattsAwesomeStuff »

Basically no change. And one was done more at night when the temperature dropped, making the air more dense.

I wonder if in an older car, a 3 or 4 speed, if it would matter more, but certainly seems on a 6-speed it matters not.
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Re: Which is the most efficient gear for highway driving

Post by johu »

Yes, that is basically the conclusion. 14.9 vs 15.1 is a 1.4% consumption drop, maybe if you factor in the higher average speed you'd arrive at like 2%. Temperature was unchanged, this all happened within 40 minutes and I saw 26°C on both runs.
The main advantage of a lower higher gear is noise reduction...
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Re: Which is the most efficient gear for highway driving

Post by arber333 »

johu wrote: Sat Jun 19, 2021 7:17 pm Yes, that is basically the conclusion. 14.9 vs 15.1 is a 1.4% consumption drop, maybe if you factor in the higher average speed you'd arrive at like 2%. Temperature was unchanged, this all happened within 40 minutes and I saw 26°C on both runs.
The main advantage of a lower gear is noise reduction...
Dont ask me, i run in 2nd gear always 😇.
With Mazda i used 3rd for urban and 4th on highway (better cooling with higher motor rpm). I found out 4th had better throttle response (inertia) than 5th and that meant higher amps for less time.
With Leaf motor in 406 i find efficiency is in the next order of magnitude. Cooling is liquid and throttle response is really good. But friend with Mazda RX8 and leaf motor on transmission has worse economy than me. Just empirical observation, no hard data here. Maybe its his foot.
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Re: Which is the most efficient gear for highway driving

Post by rstevens81 »

I call it good & bad, at we know that motor rpm seems to have a low effect on efficiency as we seem to be into to the noise with with that level of difference, so we can leave it in the same gear or physically lock it in gear and remove the gearstick if we wished.

My question is around performance that the chap with the rx8 had power drop off above 5k rpm (viewtopic.php?f=11&t=326&start=100), @110km you would probably be above this rpm in 3rd?

I was also confused (sorry silly question) when you said it was quiter in a lower gear, do you mean lower gear timber (3rd) or lower ratio (4th), I assume you were indicating that you get more noise from the inverter at low rpm?

Ps. I really wish I were in a position to do testing myself, however life (moving house and then renovating it) has slowed my project, however am am trying to use the time to try and better understanding coding and how BMS work, also I should get a reasonable sized garage out my efforts of moving 🤪
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Re: Which is the most efficient gear for highway driving

Post by johu »

Yes the car feels more nimble in 4th gear on the highway. At 100 km/h it reaches about 5000 rpm and drops in the FW. So I do appreciate the choice. Same for city driving in 2nd.
I meant to say higher gear, corrected above :)
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