Coasting vs. Engine Braking

[caveatipse]

I know some cars completely cut off the gas flow at a certain RPM when you use engine braking, thus making it more effecient than coasting to a stop. Does anyone know if the Toyota Yaris does this? Thanks.

[JanGeo]

Pretty sure it does since I have a xB and it uses the same 1.5liter VVTi engine - the way to tell is to get a scangauge to monitor the engine temperature and when the engine is still cold about 120 degrees, go down a long hill and with your foot off the gas, engine braking, you should see the temp stay constant or even drop a little if you are using the heater. This indicates that the fuel is cut off.

[GasSavers_James]

coasting is always more efficient, unless you need to slow down anyway. If you need to slow down anyway, downshifting does use a little bit less fuel. Shift to a gear where the engine is turning between 1500 and 2500 rpm (depending on how quickly you need to slow down).

[caveatipse]

Wait, I am confused. If engine braking shuts off all gas flow, and coasting allows an idle amount of gas flow, and assuming you are covering the same distance and start both at the same time, why would engine braking not use less fuel?

[Jim Dunlop]

Because you can't "coast" as far while engine braking since the vehicle's momentum is slowed down by the resistance of the engine.

[Wyldesoul]

But the engine braking is far better when coming up to a red light than popping it in neutral and hitting the brakes.

[JanGeo]

YEAH guys pay attention . . . craveatipse is COASTING TO A STOP!

[JanGeo]

If it is anything like my xB you should be able to get engine braking down to about 1000 rpm in top gear before the engine suddenly bucks as the injectors start to fire fuel into the engine. In my xB gearing that happens about 18mph in 5th gear.

[caveatipse]

Ok I should rephrase. If I am, in both situations, coming to a stop, and I can choose either putting it in neutral, coasting to a stop, then applying brakes, or engine braking down to a stop, which uses less fuel? Sorry..I did not communicate very well.

[JanGeo]

You said it right - engine braking will use less fuel only the ScanGauge will not show it until you fill it up and it takes less gas to fill than it reports you had used. Usually a few tenths of a gallon per 10 gallon fillup depending upon how many long engine braking stops / hills you did on the tank of fuel.