Quote:
Originally Posted by racprops
I had to add my 2 cents worth.
My big bad old 2000 Mercury Grand marques was able to get 28/30 MPG at 65MPH.
This was at about 2 GAL per hour. (Via Scan Gauge II)
At idle it ONLY used .45GAL per hour. IF I could get a car that used that little fuel driving it would be getting 100MPG+.
SO killing your engine is a waste of time and dangerous. Leave it running at idle out of gear; you can then simply put it back in gear when you need it.
This keeps everything working, power brakes, power steering, A/C, all gauges and lights, and there is much less drain on the battery as even an idling engine can be charging the battery, and IF you drain your battery coasting with the motor off you then pay for a heavy charging load recharging it.
The one problem with this is some car and trucks seem to have a odd thing happen, IE my Mercury and 03 Crown Vic will maintain engine RPMS at or higher that the RPMS needed at speed. Yet my 1993 Chevy Van and my 2002 Ford Explorer will drop to idle when shifted out of gear.
So unless someone can figure a way to get these cars that will not drop to idle to drop to idle, this will not work as good as it will on cars and truck that do drop to idle out of gear.
As I have not considered using this I cannot say how many GPH it was using out of gear and still revving to RPMS, could still be much less GPH as the engine is free spinning and NOT under any load out of gear.
Rich
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In my Insight, idle is ~0.19 gallons per hour. I already get 100mpg cruising at steady speed. EoC helps further, but the better your gearing is, the smaller the gains from EoC. A vehicle geared such that it's at 90-100% load at your cruising speed would probably have almost no gains from EoC, aside from those from running at the RPM of peak BSFC. Might be another 5-10%? Anyway a good, modern CVT would probably see almost no returns from EoC, whereas a sports car with very short manual gearing would have a ton to gain from it. My previous Honda would cruise at ~4300rpm at ~65mph. Steady-state driving it delivered anywhere from 27 to 35mpg. With EoC I was able to break 50mpg on flat terrain a few times.
Dangerous though? Maybe in some cars. My car weighs in at ~1700lbs right now and stops fine even when the vacuum booster is empty for the brakes. It also steers fine without the electric power steering active... but the EPS actually stays active when the engine is off, so it's doubly a non-issue. My car is just about to turn 20 years old, and most new vehicles have electric power steering now.