Decel fuel consumption

[ThreePot]

Why not ?

[Cani Lupine]

Some hills are too steep to leave the throttle in one position.

[m4v3r1ck]

Some hills are too steep to leave the throttle in one position.

Exactly the reason, and not to mention your car will heavily decrease in speed which will annoy/block other road user and on the way down it will keep giving gas which is dangerous.

[ThreePot]

Some hills are too steep to leave the throttle in one position.

Exactly! SOME hills are too steep. Actually most hills are to steep.
But...some hills are very slight, and when there's no traffic anywhere near me I let the car speed up and slow down on it's own.
I do this by holding the gas pedal perfectly still. This takes concentration, not one of my strong points.

[m4v3r1ck]

Exactly! SOME hills are too steep. Actually most hills are to steep.
But...some hills are very slight, and when there's no traffic anywhere near me I let the car speed up and slow down on it's own.
I do this by holding the gas pedal perfectly still. This takes concentration, not one of my strong points.

But the question is ... will it uses less fuel than conventional cruise control?

[ThreePot]

But the question is ... will it uses less fuel than conventional cruise control?

Excellent question !

I was thinking it drops, but I don't mind being wrong.

[MetroMPG]

Yup.

If the hills aren't too steep and you're not obstructing traffic, fixed throttle position is better than cruise control.

Cruise control does the opposite of what you want for good fuel economy: it adds more fuel to climb, then wastes the potential energy gained in the climb by backing off the throttle on the descent, using engine braking to maintain speed.

[IchabodCrane]

Where I live the hills are not too bad and I like to hold my RPM at 2000 at all times during commute.
This gives me an effective speed range of 80km/hr to 105km/hr which is not too obstructive for other vehicles.
I often wondered if there was a way to set up cruise for set RPM rather than set speed as I have gone 74 mpg (Imp)
using this technique.
note: CVT

[m4v3r1ck]

Yup.

If the hills aren't too steep and you're not obstructing traffic, fixed throttle position is better than cruise control.

Cruise control does the opposite of what you want for good fuel economy: it adds more fuel to climb, then wastes the potential energy gained in the climb by backing off the throttle on the descent, using engine braking to maintain speed.

But then again engine braking = fuel cutoff which means 0 usage. Averaging that ... than I'm still quite curious ...

[MetroMPG]

There's no simple answer to this question - it depends on many factors.