A few fuel economy questions

Alright, so I have an 06 TDi with 5mt and the 16" Biolines, and running straight dino fuel.

I am consistently getting around 40 to 42mpg when driving, both mixed and city driving, with top speeds around 110km/h and a slightly heavy foot. Is this good? I think I can get more out of this car/engine.

And here are the real questions:

1. Will the cold temperatures right now affect the fuel economy that I am getting? Its usually around -15C to -30C here in Northern Ontario.

2. What is the best engine speed to run at? I try to keep keep the engine around 2000 rpm to prevent glazing of the cylinder walls at a lower rpm.

1. Will the cold temperatures right now affect the fuel economy

Sure will, but not a great amount.

2. What is the best engine speed to run at?

You worry too much. The TDI is tough enough to handle a lot. You don't need to baby it nor do you need to drive it like you stole it. Drive it the way that makes you feel good.

I drive mine easy, others drive them like they are on the drag strip, we both enjoy our cars and are getting very good service from them.

Joe_Meehan said:

You worry too much.

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NICE!


Yeah, cloud, the uber-low temps are going to have an adverse affect on any car - - guz-o-line or deesell .

Your reported MPG sounds quite decent. Why do you worry so much

Excercise the engine throughout its entire rev band. Don't ride around like an old goat at 2k RPM....other surprises (the bad kind) will greet you in the future.

I couldn't agree more with Joe: Drive more, worry less!

cloudstrife said:

1. Will the cold temperatures right now affect the fuel economy that I am getting? Its usually around -15C to -30C here in Northern Ontario.

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Well when we had -30 few months back I got 7.75L/100km. My average without that fill is 5.8L/100km.

I am consistently getting around 40 to 42mpg

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Imperial or US gallon? 40-42 MP(imp)G = 33-35 MP(us)G. If that's the case, I would be worried.

How many miles on your car? It will do better after it is broken in. My father has a similar car to yours, and he gets about 42-44 MP(us)G or 50-53 MP(imp)G. In other words, about 5.5l/100km. He drives very gently and shifts early.

cloudstrife said:

1. Will the cold temperatures right now affect the fuel economy that I am getting? Its usually around -15C to -30C here in Northern Ontario.

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I notice quite a difference in the cold weather. Probably 10-15% lower on average, some of that due to the winterized diesel. I think the worst is a lot of cold starts in really cold weather - that seems to hurt my economy the most.

110kph is 67mph.

If you are talking US gallons, 40-42 is pretty good for mixed city/highway.

I'm getting an average of 47 mpg at 64mph or less with 90% highway with little traffic.

McBrew said:

Imperial or US gallon? 40-42 MP(imp)G = 33-35 MP(us)G. If that's the case, I would be worried.

How many miles on your car? It will do better after it is broken in. My father has a similar car to yours, and he gets about 42-44 MP(us)G or 50-53 MP(imp)G. In other words, about 5.5l/100km. He drives very gently and shifts early.

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Its in imperial gallons

And it has about 10,000 kms on it, or 6200 miles, so its barely broken in yet.

I drive a little leadfooted - try to shift before 3k, keep it around 2, although I think I can run it around 1500 when just cruising, that shouldnt be a problem.

I also worry about the fuel pumps though, I shouldnt have to add any lubricant to the diesel fuel due to the lower sulphur content these days, should I? I am thinking the engine was made for the lower sulphur content. - If I dont add it to the diesel we put into the logging equipment, we have to rebuild fuel pumps quite frequently.

Also, would running 5% Biodiesel add any more lubrication, or would it increase my fuel economy? Thats all we can get up here in Northern Ontario

WOW! No one mentioned a "front" for your RADIATOR.

Keep the radiator 90% covered at those temps, and the engine WILL purr along better, also getting more heat into the occupants and thawing them out a little .

I am using a MYLAR sheet/pieces and others are using pipe insulation for the grill area.
The VW's take most of their radiator cooling from below, also called the valance.

Maybe an old shower curtain drapped over the radiator support? (I am trying that next)
Temps. where I live are cool to cold and I get no HEAT! WAZ-UP?

I have jetta 06 with dsg and 23k km on odometer. With mixed city/highway I only get from 30 to 36 mpg. Since this week is cold -15 to -30, fuel consumption is only 28 mpg even I've added Power Service.
Can I have some advice to increase my fuel consumption...
Thanks

Normal due to cold weather.

The biggest change I see in cold weather is the tire pressure drops. Keeping the tires at 38-40 psi makes a real difference in mpg. With the up and down temps his year it means checking tire pressure at every fill.

Ya I would block that grill 100%, if not for your engine, to get you some heat as well. I used black "gaff" tape, similar to duct tape except it can be removed without leave a gooey residue. It makes a huge difference. My upper grill just a piece of plastic behind the grill, I like the "stealth" look.

Heck even last night running home I only hit 164F (73C) and I don't turn the heater on until it hits 140F (60C), but it was windy and 11F (-11C) outside

Question on radiator blankie

Hi,

you guys will laugh seeing as i'm in Mexico (new and improved), but it gets cold here -- okay, now that you're done belly rolling, santa fe gets down to the single digits consistently since it's up thar in the mountains...

Just a question on covering the radiator... wouldn't the thermostat do the trick to keep the temp up in the engine? Or does the cold air rushing in cool the engine/heater core too much despite the low circulation through the radiator. I'm brand new to the tdi world so wondering how this works. My jetta gets up to 190F on the temp and doesn't budge one way or the other no matter the temperature -- almost thought it was broken since is was so stable! cheers y'all

wouldn't the thermostat do the trick to keep the temp up in the engine?

No. There is always some bypass and frankly even with that the engine does not have enough waste heat to keep up with the normal cooling of air through the engine compartment.

On my car the temp on the dash will hit "190" or straight up when the car is about 170F on Scangauge and I am told stay there until about 210F? Basically straight up is normal operating temp. A couple of winters ago with 100% blocked (except the intercooler, which I now block as well) and -5F (-20C) the car never got above 160 no matter what I did. It was all on a 55mph highway so running maybe 60mph. As we slowed down coming in to a town it would drop in to the 140's.

I don’t think you need to worry about it if your trips are longer, like 20+ miles or it is 10F or 10C outside all the time or your needle never points straight up

165*F to at least 210*F, maybe higher. My coolant has never gone above 210*F so I don't know.

Let the car get a few more miles on it. Back off a bit on the lead foot. You should see the fuel milage increase as the engine is broken in, you "keep your foot out of it & the temps. increase. Just my $.02. Bob

On edit. Check your tire pressure. See Eagle's thread about fuel filter adversly affecting economy. A preventitive filter replacement might be warrented.

Ok, so I am curious about blocking the radiator...........It sounds like it is better for the engine to be warm than cold, I don't care about my passenger area, I like it cold, but what is best for the engine, 160 can't be bad can it? 140? Is the reason for blocking just to get temp up for comfort? Engine runs better at 190?

Thanks.

NH_TDI said:

Ok, so I am curious about blocking the radiator...........It sounds like it is better for the engine to be warm than cold, I don't care about my passenger area, I like it cold, but what is best for the engine, 160 can't be bad can it? 140? Is the reason for blocking just to get temp up for comfort? Engine runs better at 190?

Thanks.

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The engine is not fully warm until 190*F. Meaning try not to rev the snot outta it or floor it until it's good and warm.

An engie that never gets fully warm uses more fuel, the oil doesn't get as hot as it should etc. etc.

Only just a wee bit off topic....

I notice a few guys have the ScanGauge II. With that in use on my car now I realise just how poor the OEM temp gauge really is! My question is what amount of fuel are you using for the tank size for its internal calculation of fuel consumption. My own manual calculation is different than ScanGauge by a bit.
I've read the manual but am interested in your opinions.
Thanks in advance...

Depends on the ouside temp and how far/fast you go. I have not covered the front on mine but probably should. When it's around 0F it takes about 20 miles of mixed driving to get up to the indicated 190 (which according to Scangage can be anywhere from about 165-?. I've only had mine up to 185, even in 80F summer) More/faster highway speeds would warm it up quicker of course. At -30F it took about 30 miles at about 60mph and then it would stay right at 177/179 per Scangage (The dash gauge is not too accurate despite it's markings and I suppose the Beetle with the lights, well...) Anyways I think they heat real well for the amount of fuel they burn. Your water temp is up to 125 when the needle leaves the peg. And I don't have a plug in heater in this one, yet... If next winter appears to get colder than this year, well TDIHeater here I come. It is kind of interesting to watch the intake air temp on Scangage. When you work the engine a bit under boost conditions (like up gradual hills so you have time to watch) the air temp climbs as the turbo compresses more and more air.

Mileage and temps:
Yes I think we all agree tempature does affect mileage. I have only been driving diesel for two winters now and I only see a 5 MPG difference from summer to winter. Maybe southern Wisconsin dont get as cold as northern Ontario. But then again maybe northern Ontario don't get as warm as sourthern Wisconsin. So it could be a wash for that argument.