My Green Skoda Fabia (VW Polo) R3 CRTDI - finally smashed the 3L / 80MPG barrier
 

I'm going to start my modest eco-modding adventure here. My intention is not to go extreme right away. I've got a little family and the victim is our family car. The interior remains untouched. I'm also health care worker and have to make house calls from time to time, or trips between hospitals. The exterior must remain 'presentable'.
So, I'm going to make small, but efficient adjustments. But craziness comes with age so who knows what the future holds!

The car: a Czech estate version of a VW Polo equipped with the common rail 3-cilinder 1.2 TDI, producing 75 kicking horses and a street shredding 140 ft lb of torque. It feels like there is more to it but TDI's are known to have more power than specified. However, a small diesel engine requires a special way of driving ...

What have I done so far:

1. Short distances = bicycle
Already cycling 3000 miles/year, especially short distances. Those are dreadful for a hypermiler, and it's just not done for a diesel!

2. The base is already pretty good.
Hitting regularly 59 MPG in summer and a total average of 55 MPG is not bad. That's with normal, but gentle driving. The car has some stock aero features like a closed undertray and rear diffuser.

3. Grill block
Or winter cover. I only closed the biggest opening. The upper grill is still open, but already half closed from the inside. The bottom opening above the spoiler is the inlet of the intercooler, as seen in the picture.

For those interested, there are stock covers for most EU cars/vans on this website https://e-heko.com/en_GB/c/Winter-covers/1323.

4. Wiper delete
The wipers are not hidden under the hood and probably create some drag. The wiper seems to be even higher on the passenger side, so I removed that wiper arm completely. Look at page 3 for this mod.

5. Reducing weight
Removed all unnecessary weight from the car: such as child seats, rear seats, spare wheel, tools, all kind of family clutter. In total a reduction of 165 lbs. See and read more at page 4 & 12.

6. Lightweight LLR rim/tire combination
I scored some old forged aluminum Audi rims, weighing just 12 lbs a piece. The new tires are Dunlop Sport Fastresponse, a LLR tire with great handling capabilities in wet conditions. Tire size is now 175/65/15, being 11% narrower, 3% taller and 20% lighter than my previous wheels. Lowering unsprung weight is critical in improving car handling and fuel economy. Page 7 for more information and pic's.

7. Camper conversion
I came up with the idea to turn the car into a small RV for short trips. Did this by recycling and using some leftover materials to keep costs down. The result is a simple, but comfortable sleeping place for 2 people. See page 11 for this 'mod'.

8. Lowering springs
The car has been lowered by 4 cm or ~1.5 inch with H&R lowering springs. It improves handling and lowers drag - less air going under the car, better filling of the wheels wells and less frontal area of the tires. See page 13.

9. ECU 'chiptuning'
Or maximizing engine efficiency. I wasn't looking for maximum power, or a spiky curve, but higher torque and smoother power delivery - a flat curve. The software was specially written for my car and according to my wishes. The result is more than 230 Nm (170 lb-ft) between 2100 and 2800 rpm and 100 hp at just 3100 rpm. More details on page 15.


GOALS
It would be nice to achieve an average of 70 MPG in normal driving conditions, with the possibility of 90 MPG on long (highway) distances. It should be possible knowing that my very best mileage ever - before this adventure - was 71 MPG with the standard car at reasonable highway speeds (~60 mph)
In addition, I would also like to reach a top speed of 200 km/h or 125 mph with this small three-cylinder. That extra horsepower and the aerodynamic adjustments, should make it possible.

The following fact makes me optimistic ...

How the 'famous' hypermiler Gerhard Plattner set a record of 107 MPG :eek: during 1246 miles :eek: in a stock Skoda Fabia Greenline 1.2 TDI: https://www.carscoops.com/2011/05/ge...-again-drives/

I will certainly not achieve such numbers ... Or shall I get close? I'll keep you ecomodders up to date. Please give suggestions oh wonderful community!

Bigger turbo if you drive long distance on a motorway or autobahn, cold air intake for when air temperature is above about -5C, use bigger intake pipes with smooth bends, install an intercooler if you don't have one, use a block heater.

Bigger turbo: is it really that effective? I'm afraid it may increase consumption. The standard turbo has a variable geometry so the blades are adjusted depending on the engine load to deliver the best flow at every engine speed.

Intercooler is also standard and has it's own inlet, as seen on the picture of the front.

If it's got a variable geometry turbo stay with that.
How about that turbo piping, cold air or rammed air intake?

Those are things to look at, indeed. Let's see how the car is doing with minor changes first. A sportfilter could have more effect after chip tuning, when more air is required.
The air intake is already in front of the engine compartment, so it's getting cool air directly from the upper grill.

baseline
 

I set the new standard today to monitor progress before and after some of the improvements.
So finally refueled after 43 days in lockdown ... and got an average of 55,7 MPG. That's totally standard. With inefficient winter tires and some additional weight in the car like the spare wheel and material, 2 child seats and other family clutter. Quietly driven but not slow.

If you do the rim/tire mods, try for improvements in as many of these categories as possible simultaneously: overall tire/rim weight reduction, aero cover or vent blocking, narrower and taller tire/rim combination, and Low Rolling Resistance tires. It can be done. Takes a lot of research. Checkout our wheel discs showcase thread for ideas: https://ecomodder.com/forum/showthre...scs-37690.html

I do not know what the laws are where you are but the side mirrors are one area to address. It reduces frontal area and removes an obstacle from a very messy region of airflow.

Some Ecomodders have replaced the mirrors with cameras and screens. I have removed the passenger side mirror completely and I fold in the driver’s mirror on the highway. It can be quickly unfolded for city traffic. I have tuft tested it and the airflow is better with the mirror folded. I use small convex mirrors in their place. The passenger side one is inside the car. The driver side mirror is glued to the glass of the folded mirror at the correct angle with a small aluminum bracket.

That's a good idea! Nice wheel thread btw, very inspiring.


Yes, it is mandatory if the car was supplied with them. But I can replace them by smaller ones or fold them in on longer journeys.

I'm thinking about removing the passenger windshield wiper. Looking at the regulations, I see that it's allowed. Hurray!

I found an astonishing article about Gerhard Plattner who drove a stock Fabia Greenline to nearly 107 MPG on a 1246 mile trip. Assuming this is real, what could be achieved with aerodynamic and weight-reductive changes to this car, AKA ecomodding :confused: And how does that man drive? That's perhaps the biggest question.

https://www.carscoops.com/2011/05/ge...-again-drives/

It is interesting that they don't disclose an average speed, or even the amount of time it took him to do the trip, his times of departure and arrival, or the route he took.

You can be sure he did all of the hypermiling tricks that you see us doing here. It appears that he might have had an escort by some sort of police force on the highways. My bet is that he was drafting those cars. He would also have his tire pressuring exceedingly high. He would likely be using the pulse and glide driving technique and the variety of other techniques that are talked about on this site and others.

He doesn't disclose that full set of techniques, because he does not want people imitating him en mass. He appears to have a minor PR purpose in promoting to people that they day have in their hands the ability to help reduce greenhouse gases by not driving like a lunatic with a leadfoot. Strange career!

You may want to look at TDIclub.com for good information about the VW diesel. They do not recommend aftermarket cone style filters as the factory filter is already very good and free flowing. I have seen where some owners will add a second duct to the air box.
I have tuft tested the hood/windshield/A pillar/side window area send found the air is flowing forward at the base of the windshield. The wipers are in a “recirculation bubble” so nothing is to be gained there, at least on the Golf.

I suspect he is using E-Off pulse and glide to get those astonishing numbers. I do not recommend doing this in a turbo diesel except as an extreme mpg stunt. You could probably achieve those numbers in a totally stock Fabia Greenline. I plan to keep my car a long time and I would worry about turbo issues among other things.

He drove the distance mainly on the biggest highway in Germany (back and forth) in 2 days with few brakes not longer than an hour, so the engine didn't cool down. Found a video (in Spanish) about his stunt. On that footage he's not slipstreaming any car, he's going 55 MPH and at the end I see an average speed of 51 MPH on his BC.
https://www.youtube.com/watch?v=Sy1zqsAXOZE

But of course he would have used techniques that are not recommended for everyone, unless you know what you are doing (and that's a large minority, unfortunately) That may explain the lack of information.

Yes I've heard that before. A diesel engine normally gets an abundance of air to work with. Maybe if it got 100hp/liter it could benefit from another filter. That could be a test for the dynamometer when it will get the software upgrade ...


The wipers stick out a bit on my car, they don't sit under the hood but quite high on the window. That's different for every car.

Do you have brake drag reduction springs?

Nice post!!!

Is there any additional potential in your car by changing final gear ratio? What is your RPM at 80km/h for instance? Lowering rpm will result in an increased engine load and therefore a better fuel efficiency.

Looked it up ont YouTube. What a great invention! And quite easy to do myself. Thanks for the tip!

1500 rpm at 80 km/h or 50 mph. Lower rpm's in highest gear and a slight ascent of the road are causing the engine to hum. So given the standard engine output (~80 hp) 5th gear is long enough.
The cheapest way to extend the gears is to increase the tire size.
The Fabia has a 195/55 tire which is too wide and too small. Next tire could be 175/70 and would result in 1400 rpm at 80 km/h.

Got a picture of the consumption on a flat road and a windless condition at 16°C without changes (so before installation of the grill cover)
At 100 km/h or 62mph at 1900 rpm - my favorite highway speed - it was consuming 3,3 - 3,4 l/100km or 69,2 - 71,3 MPG according BC.
That's not bad at that speed.

Our stoopid gas guzzling hybrid Hyundai car would only get 48 to 50mpg at that speed with the low rolling resistance tires.
Moat people don't realize it but your diesel is actually a hybrid.

So that's why there is only room for a 10 gallon fuel tank. They filled the rest with batteries! :mad: Dieselgate was not enough, VW? :D

The passenger wiper sits higher than the one on the driver's side, and I think it creates drag. Or not? See the picture below. So I tried to remove it today, but I failed due to corrosion, there is no movement at all after the bolt is removed. Is there a trick to get this out without any special material (and without demolishing the mechanism) ? I put some WD40 on it and will try it again tomorrow ...

Are you trying to remove the wiper or the whole arm?

Some guys take that one off. I did. It is impossible for people with our tools and techniques to know what effect it really has, but it is plausible that it disturbs airflow before it moves downstream. I took mine off and adjusted the driver one to sit slightly lower in the well while at rest.

I did it! With some help from YouTube. I took the passenger wiper arm completely off. Meanwhile, I also lowered the wiper on the driver's side so that it's more in the 'bubble' and catches less wind. Thanks California98Civic for that idea!

I will also swap the current 20" wiper by a 26" one, to make up the loss of the other one (a little). It should fit.

Wipers where in need of replacement, it will now cost me less and thus compensates for the purchase of the grill cover :thumbup:

Technique of removing a corroded wiper arm (see photo's below or the movie on YouTube that helped me https://www.youtube.com/watch?v=ty1IszPwnnM
- Screw another bolt onto the post, 1/2 to maximum 3/4 (to protect the thread)
- Place a wrench or pincers under the arm to apply upward force while hitting the bolt with a hammer.

Rusted grit is released and after another few hard strokes the arm comes loose.

Good deal! Surprised that guy didn't hit the siexzed stud with a little penetrant oil first. It probably would reduce the hammering, which seems hard enough to risk windshield damage. Very clever though, especially reattaching the nut first. Nice hack.

Tomorrow I'm going to try to get my first 70 MPG trip of the year. I have done it twice since I got the car 9 years ago, the best one was 77 MPG and the second best was 71,6 MPG without modifications. But those attempts were in ideal summer circumstances, distances from 200 to 350 miles and always measured in one direction, slightly declining.

Tomorrow I have to go back, forth and a little detour for 80 miles, where I usually get ~61 MPG (63,6 MPG with only a closed grill). So it will be a challenge, considering that I will maintain speed limits and not less than 60 MPH on highways.

Mods so far:
- grill block
- tires at 40 psi
- wiper delete
- side mirror folded in

- Removed an incredible 112 pounds :eek: of exces weight (2 child seats, spare wheel, tools and all kind of stuff)
- I also closed the alloy rims with strong tape to see if it has really effect. If it turns out to be effective, the next step could be proper closed hubcap/rims.

That is a good set of mods. I suspect it won't be too hard to hit 70 mpg. Keep us posted.

Yes, me and my Green TDI succeeded!

Result: 71,3 MPG
Distance: 82 miles
Average speed: 48 MPH
Direction: back and forth
Weather: light rain, 19°C, 10 MPH wind from different directions
80% highway at 62 MPH, 20% city driving

Couldn't believe it at first because it was raining and I had bad luck at most intersections. I even had to brake on the highway for a bunch of pheasants crossing :(

I did check the actual consumption at 62 MPH on the same stretch as the last time, and fluctuated between 78,4 and 81,1 MPG! It seems to be a massive improvement: 69,2 - 71,3 MPG stock.

Congrats! I will record it under SRA class in the 70 MPG challenge OP. Woot woot!

Wow!!! Congrats it is awesome :) I am a bit jealous as I cannot for the moment go much under 4l/100km and my instantenuous fuel consumption at 62mph (real speed, so about 105 at the gauge) is more about 4l/100km. But it is true I haven't used all your tricks now and I live in the mountain. Even with much care, it can't be helped that a lot of gasoline be wasted downhill in brake dust and heat. Do you know the official SCd figure for your car? Mine is 0.60m2, and at 80km/h my engine revs at 1300rpm, which is fine but couldn't be lower.

I might try overinflating the tyres but I will only do that on long trips.

First of all, nothing to be jealous about! You have a bigger and heavier car, and your engine has one more cylinder. These cars can't be compared properly.
Secondly, my speed is 100 km/h on the meter (so 96 km/h or 60 mph real) Consumption increases exponentially with speed, even a few km/h less will do the trick.

I wonder if your engine is running under too much load in highest gear, could it be that your 6th gear is too long for 100 km/h? Especially on hilly roads. Try 5th gear for a while. (at lower gear you will also have to brake less downhill). My experience with the 3-cylinder TDI is that it loves to make a little bit more revolutions, without consuming more. I 've noticed that the 'sweet spot' for constant speed is between 1500 and 1900 rpm = I never use highest gear below 80 km/h. But then again, it's a smaller engine.

What do you mean with SCd - frontal area or Cw value? That last one is 0.32 stock, but maybe I'll have it down to 0.30 with modifications.

Keep trying ptitviet! Summer is coming...

Hello! Yeah I am trying more and more and hopefully there is a possibility of improvement through longer trips throug hotter air :)

SCd I mean the product of frontal area and Cw factor. For instance, on my car the front area is 2.2m2 and Cd is 0.27. Which gives a result of 0.593m2. I got through coastdown testing a value of 0.606, which is 2% of official value so I am happy with my protocol. And coastdown testing told me that folded passenger mirror made my SCd down by 0.02m2.

When I receive my new grille block I will do a new coastdown testing to try and see the actual difference.

So my SCd is 0.643m². It seems you're car has a much better Cd too - a longer car usually scores better and you have the optimized Greenline model. I bet you still can make a lot of progress! Keep me updated! :thumbup:

Some pic's of my last modifications. Simple mods, but with great effect.

- closed the rims with some strong tape
- removed 112 pounds of junk out of the car.

Those are standard 15" alloy rims with 195/55 tires. They will be replaced with narrow tires when they are worn out (next year). Preferably in combination with a light forged rim from Audi and a closed hubcap.
Now the tire: it could be 165/70, 175/65 or a 185/60. But is narrow always better? Assuming you could go faster trough corners with wider tires = less braking and accelerating?

There is a long-running debate about whether narrower tires are better. There are several, sometimes conflicting factors. A narrower contact patch can ironically have higher rolling resistance, but also have better aerodynamics for being part of it thinner tire in the air flow. And then the weight and the chemical composition of the tire matter. Is that wider tire also a low rolling resistance tire? What is the overall weight of the wider tire versus the thinner tire? Because if a heavier tire out further toward the outer diameter of the overall wheel, it has a higher rotating mass effect. Lots to think about.

https://ecomodder.com/forum/attachme...2&d=1589535320

I did the same to my car. It is crazy how much the VW seat backs weigh. It has enough structure to hold the middle passenger seat belt with the other seat back folded. I can carry my bicycle inside instead of out in the airflow.

It's a pity that the weight of a tire is never mentioned as a specification.
The almost worn out tires that the car is now driving on, has already lost a lot of thread and therefore weight. Also tires have the least rolling resistance at the end of their life (but also less grip which I sometimes notice).

Anyway, the new tires must have a bigger diameter to change the gearing a bit. That's another aspect of tires.
Current 195/55 let the car go 62 (real) mph at 2000 rpm.
Taller 175/70 for example, would increase it with 5% (~65 mph) at same engine speed.

So yes, a lot to think about!

@ Cocyclist:

A great space saving without the seats! And when you think about it, they are rarely used. Though, perhaps more often as the kids grow up and get hobbies or little friends where they want to play :p

Right. Bigger diameter, taller gearing, but also the weight is further from the hub so a hit from rotating mass. You can get tire weights at tirerack.com