The 3L Challenge: 79.9 MPG US over 615 miles in a Jetta TDI
 

This isn't a success story just yet, but I hope it'll become one in the next two weeks.

Let's just say I have 900 miles in front of me, and I'm taking back roads.

I want to do it with one tank, and beat a 3L/100km average (78 USMPG) for the trip.

I've had a 65 MPG tank which was 50% city and 50% highway at 53 MPH. This tank will be secondary roads only and I'll be driving 47 MPH, so I'm confident I can do it.

I did a lot of things since my last tank in preparation for this challenge:

Deleted passenger side mirror
Reworked my air dam
Added side skirts
Added full disk hubcaps
Deleted the radio antenna
Deleted DRL
Blocked the lower grills
Sealed front end gaps
Replaced dragging brakes and rear wheel bearings, packed with synth grease
Changed my MT fluid (200k miles on it) to Redline MTL
Logged a lot of data with vag-com to find best boost levels, timing and acceleration rates for my car (results were least amount of boost during cruise, max timing advance within specs during cruise, and the bsfc map was right about acceleration)

This will probably be as much, if not more, of a mental challenge than a FE one. It'll be 20 or so hours of driving at 47 MPH in four segments over two weekends.

Looking forward to updates on this. Thats a good jump in FE, but you've also done a lot.

On the highway part of my previous tank, I was pulling around 70 mpg at 53 mph.

So basically what I'm hoping for is a 12% increase in FE from a reduction of 6 MPH + all the mods I made.

The passenger mirror removed + driver mirror folded should give me 2.5%
The side skirts and hubcaps, let's say another 2.5%
The 2 small lower grill blocks + antenna + drl maybe 1.5%
Who knows what the brakes were costing me, maybe 1%

The 6 MPH slower speed should give me the other 4.5% I need.

I should add a diffuser before I leave to seal the deal.

Sounds like quite the challenge, and within reach. Here's hoping for calm or following winds! When are you leaving?

I'm leaving Saturday morning for Montreal and back in Quebec Sunday in the afternoon. The first weekend won't be too bad, only 300 miles.

Next week I'll leave Friday morning for Mont-Laurier, my home town, 2.5 hours north of Ottawa, and 300 miles from Quebec City. I'll be back Sunday in the afternoon.

It's funny you talked about the wind, that rang a bell. The road I'll be taking between Quebec City and Montreal is following right along the north shore of the St-Lawrence river. When I cycled around the Ile d'Orleans a couple years back I remember they recommended going around in a specific direction in order to take advantage of the wind which was going in one direction in the morning and the other in the afternoon. I wonder if that have anything to do with the tides. I'll have to check to see if I can take advantage of that.

I'll be stopping in Quebec City on Thursday or Friday on the schooner. Not sure if we're staying over night or not, but I'll let you know what I learn.

I'd be surprised if the wind changes direction - SW is pretty much prevailing. But I wouldn't be surprised if they generally recommended the route based on avoiding riding against the prevailing direction in the middle of the day when winds are typically strongest.

Did they suggest going counter-clockwise? That way you'd get a tailwind on the exposed south shore and some shelter on the north side as you headed back into the prevailing wind.

If possible I would recommend staying overnight, especially if you stay at the bassin louise as you'll have the chance to experience the image mill. Every night at 9:30, for the 400th aniversary of Quebec City there is a megaprojection on the history of the city. It is on the grain silos in the port. 600 metres long by 30 metres high, pretty impressive. Here's a pic

http://monquebec2008.sympatico.msn.ca/Files/3623.jpg

Yup, they did suggest going counter clockwise. Your explanation makes much sense.

Yes! I've heard about the mill show, and talked to someone who's seen it. It's likely we'll be staying in the bassin - at least that's what we've done the past few times I've gone to the east coast on the boat.

We'd have a great seat: usually we tie up to the wall at the right side of that pic.

I wish we had a bit more time to spend in the city, but we're on a somewhat tight schedule.

Back to the car, I finally took some pics of the "finished" product this morning. I have the hubcaps off atm as my commute is in the city and they are 17 inches, 3 inches wider than the rims, so they sit flush with the most outward part of the tire, but cover the valves, so I'll just install them for my trip.

http://ecomodder.com/forum/emgarage-...b36c4a1f6e.jpg

The skirts hold with 3 screws in each wheel well and black silicone adhesive.

http://ecomodder.com/forum/emgarage-...76af9fc7f3.jpg

http://ecomodder.com/forum/emgarage-...afdd9d45a5.jpg

I basjooed the front end using clear silicone and clear tape on the bigger gaps.

Nice ubolt dragging down eh? The pipe broke just after the cat yesterday, I'll have to fix that during the weekend, but will just hang it up in the meantime so it's not right in the middle of the flow for the first part of the trip.

Looks good... can't wait to hear the numbers.

I hope you did not block the driverside lower grill as its for the intercooler. 20 hours driving 47mpg, wow I know I could not do a challenge like that I'd probably shoot for 56mpg and get there in 12-13 hours but then again I have a lead foot in comparison.

Best of luck Tasdrouille. Can that u-bolt not rotate a little so the bolts are horizontal, or even on top? I know, it would make then harder to get a spanner or socket on but might be worth a try. You could even try a large jubilee clip. (is that what you guys call them?!) That would be clean and the bolt on that would be most accessible when on the side of the exhaust.

ollie

Yes I did, and I knew what it was for. I wanted the aero advantage, and I also like the side effect of warmer air. I was a bit deceived by the result on the IAT increase from the block though. Last week it was 85 F when I did an hour of highway testing logging stuff with vag-com, including IAT. Even with the intercooler fully blocked, I could not get IAT to go higher than 115 F with the kind of driving I do. I would like something closer to 150 F. I removed the snorkel between the fender and the airbox to help with that, but haven't looked at the IAT again yet.

If you want to pump hotter air into the engine then just bypass the IC. :eek:

That's an option, airflow in the intake would also benefit from IC removal. But it was easier just to block external airflow to it and remove the snorkel. Plus it's fast to put it back stock if I need to.

The first weekend's over, and it did not go as well as I hoped it would. I had to do a bit of city driving while in Montreal. I drove 400 miles and I'm a bit short of the half tank mark, which should come around 450 miles.

I'm over 70 MPG so far, but it's not quite the 3L/100 km (78 MPG) I was shooting for.

Back roads have some disadvantages. The quality of the rolling surface is frequently not nearly as good as highways, which can have a significant impact on rolling resistance. And every small town you go through have a stop sign or two.

On the other hand, I would totally fall asleep on the highway at that speed, but on back roads there are so many things to look at. I've seen a lot of nice places, and even if it took me nearly twice as long as if I had taken the highway, I feel it was worth it.

With 600 miles remainning next weekend, we'll see how far I'll make it on the tank.

Time to pull out all the stops! Best of luck.

ollie

Success!

991.4 km and...2.94L/100 km that's 79.9 MPG over 615 miles!!!

Average speed for the tank as per scangauge was 40 mph. Max speed was 81 mph coasting down a mountain.

Here's the car with the wheel covers on.

http://ecomodder.com/forum/emgarage-...d19ab52479.JPG

I used mostly DWL, but climbed the hills at best bsfc and coasted down with the engine on all the time.

I should really get rid of my winter tires...lol

Congrats on breaking the 3L/100km barrier, tasdrouille!

I can't deny I'm quite envious. My TDI's having problems breaking 50mpg steadily, mostly, I think, due to the (once again) bad Mass Air Fuel sensor.

Your pictures show well enough what you've done aerodynamically, but, can you give more specifics about the driving techniques?

What sort of engine load do you try to maintain while accelerating to cruising speed?

Do you use cruise control to maintain your steady speed, or do you rely on your foot mainly, to hold a smoother cruising speed?

Is your speedometer slow compared to Scanguage's kph output, like mine?

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I'm asking these questions given that most of the TDI engined VWs tend to behave similarily.

And in my case, the only difference between our cars are the level of aero modifications, the one year different model year (2000 A4 vs. your 1999 A3), and my full sized spare is on, so I only have three winter tires right now.

I accelerate at 85% load to get up to speed. When I have to climb up a big hill I do whatever it takes to maintain the engine at 1750-1800 rpm, up to 90% load. If it's a big hill and I reach 90% load I will just let rpm decrease progressively to 1500 while maintainning 90% load and then downshift at this point.

I seldom use the cruise control. I use it only so I can move my left leg around a bit as it's starting to stiffen after some time of only playing with the go pedal.

Even on totally flat ground I don't like the cruise control at low speeds (40 mph) as it have a hard time finding its speed and the car is kinda jerking back and forth. I will usually just pick a load and stick with it as much as I can, playing with the pedal to adjust the speed so I maintain a steady load.

My speedo is faster than the sg output. SG speed it 5 kph slower than the speedo. The speedo is off.

Yup, our engines are pretty much the same up to 2003 model yeay. Your car is heavier and have a bigger frontal area unless I'm mistaken, but the impact should not be all that great.

Wow, congratulations. An inspiring achievement!

Congrats Martin! That's a great pic of the mods, too. The car has a bit of Mad Max in it.

Amazing run! Congrats.

Under 3 on snows! Awesome!

On snows with a front brake dragging a bit. Next summer I'll get new front brakes adjusted for lowest drag and mount a decent set of all seasons.

I would love to get a taller 5th in there, but I'd have a hard time justifying that expense.

Absolutely incredible, it just shows how god diesels are compared to a normal gas engine. Now if only VW would bring out a diesel hybrid we'd see over 100mpg in a production road car that isn't a Metro :)

I came across a PSA (Peugeot-Citroen) diesel-hybrid,

CITROËN - C4 Hybride

This almost manages 3.4l/100km "average".

No doubt other manufacturers are going the same way, at least in diesel-friendly territories...

Martin, sorry to steal your thread.

Today diesel are consuming 20% less than their gasoline equivalent. As the prius is rated at 4.3 l/100 (104 g/km CO2), a diesel prius should be consuming 3.44 l/100 (91 g/km CO2). As these cars are smaller than a prius they are not doing so well, but they may be the best while Toyota doesn't sell any diesel hybrid. The HCH2 is rated at 4.6 l/100 (109 g/km), so a diesel HCH2 should be consuming 3.68 l/100 (98 g/km).

PSA (the Peugeot/Citroen group) is talking about hybrids since years... We are all waiting for them to actually sell hybrids. Currently only the CITROEN - Stop and Start system is sold only on 2 Citroen specific models and is very expensive.

If their prices are competitive with prius' one, ie not more than 10% over a prius, then if I have the money, I may buy one.

Denis.

Congratulations, that is quite an achievement.

Sorry about thread hijack but I am not with Groar on the diesel hybrid.
To have both a diesel that is compliant with euro 06 and an hybrid will make the car very expensive to buy compared to a petrol + hybrid and even to a full electric car.

Maybe the hybrid will allow the diesel not to be compliant with euro 06 as the car will still be OK but that is very big MAYBE

As for the Jetta, the very good thing it is still looking pretty standart.

Congrat's again !

Wow! Excellent job in your Jetta! I would love to have one just like it. I like your skirts, front air dam & grill blocks. In the winter it's a snow pusher!:D

Keep up the great work in your TDI.

Dave

LOL talk about a thread bump!

Any updates?

At least it's fun stuff about the tried & true diesel! Success stories about oil burners RAWK! When this high mileage Toyota of mine croakes, I'll be looking for a diesel something or another. I try to check out all the diesel posts just to learn what to be on the lookout for!

Keep 'em coming guys!:thumbup:
Dave

Too bad we don't get Diesel Toyota Tacomas in this country ... as Top Gear has shown, those things are indestructible. They even took a number of them on the first vehicular trip to the North Pole, if I'm not mistaken.

But which "North Pole"? Magnetic North is quite a bit further south of the geographic pole.
Still, viewing their trip to magnetic north was an entertaining evening.

I no longer have that car. I miss it, just as I miss the 91 TD I had before. I'm working to get the best out of my mk4 Jetta TDI now.

Oh i wondered, it's still in the headlines though!

So a 99 a3 would be a great one for fuel MPG'S?

The 90 HP TDi ?

I've been getting 52 mpg without really trying, in a car I wasn't used to, loaded with 2 people + luggage ...

On another trip (mainly motorway) 50+ mpg, despite doing 90+ mph at times and going over the Alps.

it would seem to me any modern diesel is going to fetch outsanding fuel economy.

I thought you had a 3000cc engine. Must read further.