Idling versus Shutting Off the Car

[philmcneal]

i've already got a simple experiment in mind: compare mpg from idling/neutral coasting to engine off coasting over the same city route.

Looking forward to it.

[MetroMPG]

went out to do some errands this afternoon (first time i've used the car since... sunday??)

so, i incorporated the comparison test between engine on VS engine off coasting into my drive.

i'll post the details later. but the figures are so good, i wanted to get them up here for your enjoyment. the fact is, i'm having a hard time believing they're accurate.

first, i can report that the kill switch works as hoped in practice: it kills the engine; doesn't put the scangauge to sleep; all the instruments (speedo/odo) continue working; and the engine can be key-/or bump-started with no difficulty afterwards.

i will have to get used to the switch though; i left it "off" by mistake a couple of times, causing me to miss one bump-start opportunity and forcing a key-start. krousdb - i can see the utility of an "interrupt" switch as you had set up. but i'll learn to use this properly since it can also serve as a simple security device.

(btw - bump start is inappropriate terminology for the technique; there's no "bump" when done correctly. we need to come up with a better term.)

anyway, the figures:

10 km loop; 100% city driving (stops every 3-5 blocks); several small hills; 3 longer hills; approx 17.5 to 18 minutes to complete each loop

light drizzle; damp/wet roads


60.3 mpg (US) - "engine OFF while coasting" loop
53.4 mpg (US) - "engine idling while coasting" loop

car was warmed up prior to test.

also, the warm weather has blown in from PA, apparently:

Conditions at SUPN6 as of (2:00 pm EST) 1900 GMT on 03/10/2006:

Wind Direction (WDIR): SW ( 220 deg true )
Wind Speed (WSPD): 22 kts
Wind Gust (GST): 25 kts
Atmospheric Pressure (PRES): 29.44 in
Air Temperature (ATMP): 45.7 °F

[krousdb]

Originally Posted by MetroMPG

60.3 mpg (US) - "engine OFF while coasting" loop
53.4 mpg (US) - "engine idling while coasting" loop

Sounds about right. I would have guessed 10%. As for renaming the bump start, nothing catchy comes to mind. I was thinking momentum start or clutch start, but those sound awkward.

Originally Posted by MetroMPG

also, the warm weather has blown in from PA, apparently:

Conditions at SUPN6 as of (2:00 pm EST) 1900 GMT on 03/10/2006:

Wind Direction (WDIR): SW ( 220 deg true )
Wind Speed (WSPD): 22 kts
Wind Gust (GST): 25 kts
Atmospheric Pressure (PRES): 29.44 in
Air Temperature (ATMP): 45.7 °F

Glad to be of service. Would you like me to send you some more? :-)

[MetroMPG]

Originally Posted by krousdb

Glad to be of service. Would you like me to send you some more? :-)

yes please, keep it coming. (i'm sure you're tired of me sending weather in your direction.)

re: bump start... how about "stealth start"?

[Matt Timion]

Originally Posted by MetroMPG

re: bump start... how about "stealth start"?

How about "running start?" LOL

[MetroMPG]

yeah running start could work too. except it's not really running when i start it... and when it is, it makes that terrible sound

i just did another short city trip. both legs were cold starts (drove about 4 km, parked for 40 minutes, drove back again.)

used the on/off switch a bunch of times, and managed 51.5 mpg round trip. on a cold motor. in city driving. that rocks!

why did i wait so long to try this? (if it's for real.... will have to wait a couple of weeks to see what this tank says at fill-up time)

currently the switch is duct taped to my shifter, dangling wires everywhere. flick of the thumb does the job. very ergonomic. ugly as hell too. i may have to fix that up.

i'll write up a proper description of the day's events and post a new experiment thread.

[MetroMPG]

Originally Posted by MetroMPG

i'll write up a proper description of the day's events and post a new experiment thread.

experiment thread posted:

http://www.gassavers.org/forum_topic/coasting_experiment_engine_on_vs_engine_off_on_a_f ixed_route.html