Consumption at idle

[groar]

I had to try a Renault Twingo during one day [1] :

• diesel 1.461L 65hp
• manual 5sp
• 3 doors
• rated 45.2 (city) 61.9 (highway) 54.7 (combined)
• CO2 113 g/km.

I plugged my SG2, which is incompatible with my 2 older Renault, and it was nearly fully compatible. It was missing TPS so the SG2 didn't had the open/closed loop information...

As I didn't know the cubic capacity when I plugged the SG2, I configured 1.6L, so the following figures are what I remember multiplied by 1.461/1.6.

I didn't had time this day so I have only been able to test the information I do not have in my scenic : the instantaneous consumption at speeds under 35km/h (21mph).

When the engine was started, the consumption at idle was at 1.65L/h (0.43gph). Ten seconds after it was down to 0.9L/h (0.24gph). After 1/4h of stop&go traffic, the consumption at idle stabilized at 0.73L/h (0.19gph).

Another thing I wanted to know is how much consumption the car has when you drive in 1st/2nd gear with the engine at idle (ie you doesn't touch any pedal). The results were :

gear	L/100	km/h	mpg	mph
1st	18	8	12.9	5
2nd	9	15	25.8	9

At these speeds, coasting in neutral would consume at 0.73L/h (0.19gph) :

km/h	L/100	mph	mpg
8	9	5	26
15	5	9	48

The conclusion is that at low speeds it's certainly better to pulse 'n coast in neutral than keeping the engine in gear at idle rpm.

[1] the megane had a leak near the water pump, the thermostat melted in part and the temperature gauge was shifted down. As I didn't drive this car since months I though the low temperature shown by the gauge was because of near freezing temperatures and short commutes (20 miles). I worried when i saw the gauge going up & down... I had then not enough water in the cooling system. Happily it wasn't the water pump, but the water tank and a pipe.
Even without front grill (removed because this problem) and heating system at full load (in the hope to remove as much heat from under the hood) I achieved 43mpg, only 10% under my summer tanks

Denis.

[FastPlastic]

Good find!

Must be nice. Mine is in the range of .69gph at idle. Which I think is the main reason most SUV's get junk for gas mileage.

[i_am_socket]

In the few minutes my MPGuino was working yesterday, even not-quite-calibrated, I noticed that with the car not moving at idle it would consume less gas in neutral than drive. (.43 gph in drive, .35 gph in neutral)

[binarycortex]

I have a 98 vw new beetle 2.0L gas 4cyl. it is around 0.28gph at idle which is 810rpm ish.

[cfg83]

groar -

Cool! I love the first-gen Twingo design. The cute name totally fits the car's looks. Wow, 65HP is only 5 more HP than my Dad's 1971 Karmann Ghia.

My 1.9L engine shows about 0.3 GPH at idle (under 1000 RPM).

CarloSW2

[holypaulie]

My Civic' 03 1.7L fully warmed shows 0.2 GPH at 750 RPM.

[taco]

i get .35 in my 98 taco(2.7l) at 650-700 rpm (when warmed)

it would blow my mind to see .1gph

[akashic]

My Tacoma gets the same. (As it should.) Though when I coast in neutral on the highway, I get .44 sometimes. Maybe all the time... I need to check more often. Does yours do that? Why would that happen?

[cfg83]

akashic -

Originally Posted by akashic

My Tacoma gets the same. (As it should.) Though when I coast in neutral on the highway, I get .44 sometimes. Maybe all the time... I need to check more often. Does yours do that? Why would that happen?

Is the idle RPM also higher? My "idle RPM in neutral" will be higher at freeway speeds. I think it is something the ECU/PCM does.

CarloSW2

[taco]

Originally Posted by akashic

My Tacoma gets the same. (As it should.) Though when I coast in neutral on the highway, I get .44 sometimes. Maybe all the time... I need to check more often. Does yours do that? Why would that happen?

Yea I get .45gph at coast even with my 5 speed.

a