mpg vs mph: prius graph

[MetroMPG]

i REALLY want to do this for my car. seems like pretty important baseline info to have for any car.
i did a quickie a few weeks back - covering just 3 speeds, though.

i'd like to know this info for top gear from, say 55 km/h up to 105 km/h in 5 km/h increments.

i almost did this on saturday morning, because it was very calm, wind-wise. but had other projects underway already. probably my next calm-day data-run.

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commenting on the prius graph... i don't understand the sharp drop around 42 mph. i suspect it has to do with the ICE being spun up to protect the MG set from overspeeding. but if that is the case, are the MPG figures at lower speeds electrically assisted? krousdb, can you comment?

[SVOboy]

I think dan said that after 41 mph you can't force it into electric only mode.

[JanGeo]

What you are seeing is the system overhead losses at really low speed - it takes a certain amount of power to get the motor to run. Then it peaks at the max speed of pure electric power as air drag started to build and the ICE kicks in and then the linear drop in MPG as you increase speed. A very interesting graph.

[krousdb]

Yes, at low speeds the effect of the system overhead is pronounced. By system overhead I mean all of the electronic gadgetry. The drop at 42MPG is the engine overhead, the cost of spinning the engine even when it isn't needed. You can achieve electric only over 42MPH but the engine still must spin, even though no fuel is being consumed. Someone has named that mode "warp stealth".

I find that graph to be consistent with my results.

[philmcneal]

if speed limits were at 40 miles per hour, and the road was flat, 80 mpg (scangauge and MAP is less than 5.0) for me easily in 5th gear spinning at 1800 rpms.

[MetroMPG]

see related graph: speed vs mpg - metro

http://www.gassavers.org/forum_topic/mpg_vs_speed_metro.html