Ideas and guidance
 

Hi all

I have done a few things to make my car (2003 Mercedes C220 CDI coupe) more efficient.

• Run Tyres at max sidewall pressure
• Stop/Start buttons to allow for maximum EOC and no idling at traffic lights.
• keep the car empty most of the time
• run with the AC off
• 80% Grill block
• Recently serviced with thinnest oil that meets spec (0w-30)
• Warm air intake.

I do a fair few local journeys, and my last tank avg was 49 Imp MPG.

By stopping the engine at red lights and using the buttons has improved my town mileage by around 8-15MPG!

I am thinking of installing a Webasto diesel fired fuel heater. This will allow me to pre-heat my engine to 88Deg C using very little diesel. This should help for the smaller journeys and can be done with a remote control.

I am also going to be putting insulation blankets on top of the engine to keep it warm.

I am getting 65-75 Imp MPG on my common motorway journeys (mostly M25 so not exactly flat).

Is there anything I can do that I am missing to push that to 80-85mpg?

Since it's a diesel the warm air intake and blocking the intetcooler may be hurting you.
Do install the heater.
I have been to London and the climate is pretty mild.

1+ on the pre heater . Eberspaecher only burns .11 usg per hr with a normal run time of 15min (from an install teck).
https://mbworld.org/forums/attachmen...-cdi-front.jpg
This image of a car in HARD cornering (Driving without brakes ecomodder style) shows that there is room for more air dam not much.

Alinment....
"Neutral" alinment. They normaly set the alinment for least driver input, =increased scuffing/resistance

Minimize use of "Defrost "settings ( plural) the system uses the AC compressor to dehumidifing the warm moist air before blowing it on a cold windscreen.

Belly pan /side skirts/ lowering
This new of a European car I assume the pan is mostly complete. Fill and smooth the under side.

The IC is open (bottom section of the rad). The top of the rad is blocked.

Will think about the the warm air intake. IAT's are still low for this car. Will defo do the fuel heater.

Excellent.

I have the full undertrays. Its not cold enough at the moment to need the defrost system at the moment.

I may think about lowering it, I just put 2 new rear springs on it though so...

Will definitely use the webasto, even on warmer days, to pre heat.

The intake air temp going into the engine only needs to stay above about freezing.
Below freezing hurts fuel economy and above about 90°F hurts fuel economy and power.

Spoke in depth with a Cummins teck, he said target IAT is above the temperature the grid heater/glow plug/cold start aid is disabled. In my case 45°- 60° f is ideal , or as close to ambant as possible if above 60°. Check with Mercedes what temperature your cold start aid is disabled.

The colder the air intake in a Diesel, the better. If you could set an adjustable air box, similar to what is used in some carburettor-fed small aircraft, that would be better than a WAI since it would allow you to select a warmer intake for cold start and restarts on stop-and-go traffic and pick colder air while cruising.

Thanks for the input all.

Suppose it make sense. I was trying to keep the engine from cooling down on longer journeys. Suppose it hurts more than the thermal issues. I will re-install the inlet plumbing to see if I can push 80 MPG.

Hopefully that, combined with the Webasto pre heating, should net me good gains.

Staying at operating temperature when it's cool out is a diesel car problem. It takes so little power to move the car and the diesel can be too efficient for it to stay warm.

Agreed.

My thought process was: If I can keep the cold air out of the engine, then it will warm up quicker and stay warmer.

I suspect it would be better to have switchable intake system, where I gave it warm intake air until a certain temperature, then switched to cold intake for more power/economy at highway/motorway speeds.

I have re-installed the cold air intake, and cut a small section in my grill block so that fresh air can get to the intake pipework.

I use the defrost as a temperature maintenance assistant. When the motor is cold I run the defrost. This duse 2 things .
1 it puts a load on the motor , because more load means more heat is generated per combustion event. Equals more heat being put into the coolent.
2 the heat productionin the freon from the AC compressor is dissipated directly in front of my intercooler and be hind my grill block witch in turn warms the intake air charge ,witch inturn warms the engine at a slightly faster rate . Allowing me to reach efficient operating temperatures faster. The hard part is to remember to switch the controls over to a non AC compressor setting when warmed up but cab heat is still needed. Forgetting tends to offset any potential.
Disclaimer.
I have an old non-computer diesle. So I can not verifie if this actually saves fule . But it duse take less time and miles to reach 100°f coolent. (The temperature my digital temperature gage starts to register. )

One mor tip I forgot. Get a data loger , ScanGauge, tork app with obd2 dongle. Seeing what a particular habitd use to fule consumption is the best way to retool the nut behind the wheel were we typically see the most gain in FE.

Dreem big chisel down to reality

Thanks!

This car has a heating element in the block that is switched on under high loads. This can help to heat up the coolant but I think its an inefficient way of getting heat into the coolant. I think it is primarily done to give the passengers hot air quicker!

I can also turn on the AC defrost as you say. Not a bad idea that, as you say, it will heat up the engine compartment too (mine is fully blocked nearly).

I have an ultragauge, but its not giving accurate mpg numbers on the diesel. It appears to be unable to detect injector cut off.