Well from what you describe it sounds like the Edmunds staff is pretty stupid. It seems really odd that someone would put their car in neutral and then "ride the brakes" down a big hill. Most experienced drivers would keep the car in a low gear to reduce speed without putting much strain on the brakes. You could still turn your engine completely off and save gas, and even if you leave it on but just don't press on the accelerator it should not use much gas. Shifting to neutral if it means "riding the brakes" is something only a few very foolish people would do.

The fact that someone on the staff posted such an idiotic experience would cause me to be skeptical of anything else they come up with.

 

I agree that what they did was dangerous and pointless, but it raises a question that I have been pondering. Am I correct in thinking that for a normal NON-hybrid car the fuel injection shuts off the gas completely when you take your foot off the gas and the car is in gear?

If this is correct it seems to me that if you are in a NON-hybrid going down a long steep hill or in a situation where you want to slow down fairly quickly you would leave it in gear, take your foot off the accelerator, and use zero gas.

If you are in a situation where you want to coast without slowing down (say a gradual downhill), you can put it in neutral, take your foot off the accelerator, and the engine will idle, burning a small amount of gas.

Or in the latter situation you could turn off the ignition and stop the ICE but then you might lose power assist to the steering and brakes.

Is this correct for NON-hybrids?

 

Some vehicles inject no fuel, or less fuel when coasting in gear. I know my '03 Civic Hybrid actually injects fuel in gear -- it does not go into fuel cut mode, according to the instantaneous mileage gauge -- switching in and out of gear makes no difference in the displayed mileage. Also, when the battery is fully charged, as 3 out of 4 valves automatically, the difference between being in gear and neutral is almost nil. The car does have significant "engine braking" however due to unrequested charging of the battery (even when not indicated by green bars)

Fuel cut or not, if you are going fast enough to require braking, it is always better off to downshift and engine brake, and thus save on brake pad wear and tear -- conserving momentum makes no sense if you are going to stop anyway.

Another argument against rolling in neutral seems to be that less fuel will be burned if the car is coasting in gear because of fuel cut (on some vehicles), however, these arguments seem to always neglect the fact that leaving the vehicle in gear down a grade generates a lot of resistance on most (non-hybrid) vehicles, causing the car to lose momentum. The other argument is that if it is necessary to suddenly accelerate hard for some reason, the driver will need to put the car in gear first-- though I don't see how that's any different at all for a manual-transmission driver who would likely need to downshift from 5th to 4th or 3rd to accelerate quickly, anyway...

 

I'm not positive, and I've searched without getting a definitive answer, but I don't think my tacoma cuts off fuel if I'm in gear and engine braking. I have found info that says some vehicles do but not at low rpm. For instance a Dodge Stealth will cut off gas if you let off the throttle at 5000rpm, but not below.

I do a lot of coasting in neutral, and my scangauge seems to indicate that the fuel doesn't cut off if I'm coasting in gear. Then again the scangauge is estimating fuel usage so I can't say for sure from that.