A 25% reduction in highway fuel consumption is impressive. Even more given the car looks so stock still.

I mean, with the lowering springs, moon discs, white walls and roof rail delete it got a simple yet unique vibe

The car actually looks really good, like the concept sketches they do when creating designs.

I am very surprised with how large of an efficiency gain you had! Great work. Have you done this to your current daily driver?

Your car looks like a futuristic concept car from the early 2000s, and I love it. It reminds me of my childhood days when I would spend hours staring at concept car photos.

Martin, please keep doing what you’re doing. Love your videos!

About 20 years ago I did a similar experiment on my historic race car. I removed the wing mirrors and wipers, taped up the front panels and part of the front grille. It certainly helped reduce the lap time. The idea of using foam between the panels sounds very good and better than using "helicopter tape" which left a mess to polish out.

Loving this. I've got a Touran converted to electric where low drag is even more important. The exhaust duct and air intakes are already closed off because we barely generate any heat at all. But that is only 2 of your 15 measures completed. Thanks for the inspiration!

Even though I would not go this far on my cars it's nice to get some inspiration and see how much the modifications improve aerodynamics.

The content level is pleasing and precise. Clear data and both including metric and imperial units. Bravo.

The 1.9TDI PDE is always remarkable in its fuel economy. A relative of mine has a 131hp 6 speed 1.9 in a Sharan, which is the biggest actual "car" you could get, maybe the Caddy Maxi is longer yes. But above that was the busses / transporter vehicles you could say. Well back to the story, despite being a very high and a moderatly long car with a huge windscreen, it is driven without every thinking about it, with 6,5l/100km. If you drive constantly with a little effort then 5,X is no problem. I drove it once and got 4,3l/100km on a 80km trip, 20km country road, 5km city, 55km Autobahn. But I also only drove 90-105km/h, much less than you with 130. Still for such a big car, I am always surprised, and it is not even really slow, the 1.9TDI has a lot of torgue until 2500rpm. VW was a very early adopter of offering 6 speed gearboxes even in cheaper cars and smaller engines, not just in sports cars.

Great stuff. I did a similar project a few years ago with a Polo 1.2 TDi. Got it basically for scrap money so hadn't anything to lose really. I stripped a lot of weight out as well. Was able to push over 100mpg out of it

Great instruction video 👏🏻 I’m glad KZfaq brought me here:D I’ve been considering similar modifications on my daily drive Škoda Felicia 1.9D for a while. First mod after new tyres was upper vent cover, and now I’m planning to cover more underneath parts

Interesting. I've thought about doing something similar, but didn't think it'd be worth the effort. 20+% improvements definitely seems worth it, thanks for this.

I’ve seen videos doing this, but seeing someone more qualified is a lot more intriguing.

This is very cool! Thanks for sharing, I’m impressed with the gains!

Very thorough explanation, and a good do-it-yourself project. I would like to have seen your fuel mileage after you repaired/serviced the engine, but before your aero mods. Cheers from Canada.

So much stuff that a layman like me wouldn’t think of! And interesting to hear your process.

Love the video - great job man. Thank you for the time and effort.

Would be nice if you had measured change in efficiency with each individual mod. Still pretty cool to see efficiency mods like this, and thanks for not making the video longer than necessary

I always wanted to do this So cool to see someone actually do it Awesome work And the car came out looking AMAZING as well

You have presented it very well like a case study project

thats really cool. well done

Engineering at its best! Absolut genial was du da gemacht hast! Ich wäre extrem interessiert an einem leichten, minimalistischen, schwach motorisierten Kombi der auf Effizienz getrimmt ist. Ein Freund von mir hatte einen Renault Megane BJ 2015, 1.5dci mit 6 Gang HSG . Wenn man den sparsam fuhr (Tempo 90-100 auf der Autobahn) merkt man dass das Kühlwasser nicht auf Temperatur kam. Wir vermuteten immer dass das Auto mit dem selben Kühlpaket wie der 1.9dci ausgestattet wurde. Trotz lausiger aerodynamik konnte man den Megane problemlos mit 3.6l pro 100km fahren. Im Alltag mit Tempo 120-130 lag der Verbrauch immernoch bei respektablen 4,3l pro 100km.

Years ago I did a fair amount of sealing around the radiator combo of a Volvo C30 for the same reasons you give here. Removed everything before selling the car too. I did some tufting on the rear hatch but decided that any modifications there would be too eye catching. I had experimented with tufting before on a glider's wing, to help with turbulator strip placement :)

Nice video. I have the same 1.9tdi passat. Learned a few new things about it :D Thanks!

Very interesting, thank you.

Easy and informative! Great job, as usual!

I love this. Inspires me to follow your thinking path.

Excellent work! Very thoroughly and thoughtfully done! I know the exercise here is only aerodynamic improvements fit for your use case with a stock drivetrain but I would have been interested in additional modifications such as optimizing top transmission gear to sit at the most efficient RPM when at 80mph or other mechanical improvements and trade-offs.

Well explained! Thank you.

That's really impressive! I'm definitely going to fit the engine undertray that was missing on my car when I got it!

Great video. Done this stuff to my Lexus 10 years ago. People this does work.

Good info, Thank you!

Nice video. It helps!

Amazing efficiency results!

Sehr schön gemacht!

you made the design better.

Great ideas thank you

Very cool! nice to see such a video, gives plenty to think off ;)

Awesome! I didn't expect it to be that much more efficient. I also think it looks really sleek and cool without the roof rails and with the moon disks!

Excellent engineering effort

that very cool way make car how you need it mi respect

I’m glad you were able to close off so much without the heat becoming an issue for braking, and engine cooling.

Very intersting! Roughly 20% better, impressive 🏅

Stark durchdacht und das Optimum an Effizienz rausgeholt Tolles Video 👍🏻

Great explanation

The Passat Variant already had a good (for 2006) drag coefficient of I think 0.29 or 0.3 (there was a Bluemotion version that even lowered this by 10% or so). Your modifications go even further and you may have been in the 0.25 range, possibly even lower. My current car, an 150HP TDI Arteon Shooting Brake, which is at 0.26, uses around 5.5-5.8l/100km with a not insignificant city driving ratio. I can easily dip it below 5l /100km, depending on the route and traffic. I find that quite impressive, considering this car is physically larger, weighs 1700 kg, has fat tires (235/18s), all modern creature comforts, safety features and is loaded with tech.

First hot glue mention I obviously have to be: "oh well armchair this and that... Temporary at best... No good" Later on: "and then I just sat the rack back on and all the holes in the roof opened as if divinity" I actually stood and applauded. Bravo.

That's really cool

Good job, man! Additionally, you can further improve the drag coefficient with more aerodynamic outer mirrors, changing the door handles for flush ones and lowering the windshield wipers into the bonnet. Thanks for your valuable contribution.

This was way more interesting than I expected

thanks for share!

I changed tire size from 205 to 185 and the fuel economy improved a good amount, less rolling resistance, I also installed turbine wheels from an older Mercedes that look similar to your moon discs.

You sir are a LEGEND.

this is the sort of modification im into. something cheap and practical that won't drastically change the car from its stock specs.

Excellent

Thats the awesome part of being an engineer and know what u r doing

Amazing video!! I Really Liked it. I wish you could do more of this videos. It would be great if you could do something similar modifications to an electric vehicle and see how Further it could go

Sehr interessantes Video, ich bin grad in einer sehr ähnlichen lage und optimiere meinen T4 1.9 td auch auf Verbrauch. Die Aerodynamik habe ich noch nicht angepasst, bin aber durch Anpassung der ESP und durch eine sehr lange Übersetzung jerzt bei 5,2L bei 10% Stadtverkehr, 20% Landstraße und 70% Autobahn bei 100km/h. Durch einen größeren Pumpenkopf und Anpassung des Spritzbeginns habe ich den Mitteldruck erhöht und den MFB50 näher an OT gebracht. Das Fahrwerk habe ich auf eine möglichst gerade Spur eingestellt und die reifen (195/65r15) mit 3,8 bar bei maximalem Druck. Ich fahre täglich 180km Strecke zu meinem Ingenieurspraktikum wo ich in der Motorentwicklung Arbeite und am Wochenende 380km in die Heimat.

New subscription great stuff

amazing, how much I learned about aerodynamics

Fascinating

Awesome videos and great enginerring. I have a VW Polo with the 1.6 TDI. Like the last one ever sold. These engines are so awesome. Had the Passat with 1.9 TDI as well. Just awesome quality. I can use some of your ideas.

I like the sleek look

Really nice! So, now I'm curious to see what you've done with your current car 😊

Interesting. Thank you

Very interesting, never knew about the downhill-in-neutral-braking-while-towing test. I can do just under 6l/100km in my 1.8l 94 monopoint Passat limo on longer trips. Bet there's a lot to gain but I like it how it is

This is awesome! I showed my dad, he drives a 2010 Passat wagon with petrol engine and DSG. He says he gets about 33mpg US at most. Similar climate in SE WI it sounds like, but his driving is a lot more urban than yours. Still, some cool ideas and the car looks good too!

nice results.

Tolles Video! Wäre unheimlich spannend zu wissen wie viel einzelne Veränderungen ausmachen. Die Felgen und die Tieferlegung alleine dürften schon grosse Veränderungen mit sich bringen.

First time I have watched a "video" with only pics. I dont even have a Volkswagen but this got me hooked. A

I've seen this being done to other cars too and now I kinda wanna get a car to do this with. Tbh the moondisks with the whitewalls look pretty good on the Passat of this generation as well lol

Ein Ingolstädter Audianer, Reife Leistung! Grüße aus Neckarsulm

I absolutely love this video! It would be really cool to see a build series of you modifying a car for a similar purpose!

Great job. It would be interesting to measure the impact of every modification and known which one make the greatest effect. Did you do some modifications in your current car? Looking forward to it

Das ganze hat mich inspiriert auch etwas an meinem Fahrzeug zu verändern (Golf 7 GTD Variant), auch wenn es das exakte Gegenteil ist. Mein Problem waren sehr hohe Öltemperaturen bei Vollgasfahrten. Ich habe also alle Dämmungen entfernt und den Unterboden gewechselt um mehr Luft in den Motorraum strömen zu lassen zudem habe ich auch das Öl zu einem dickerem gewechselt um den Motor bei diesen Fahrten zu unterstützen. Seit dem bleibe ich wenigstens unter 130 Grad Öl. Den Rest muss der Ölwechsel alle 7000 Km richten. Der Verbrauch ist natürlich gestiegen. Die Woche über bin ich eigentlich nur innerorts unterwegs, hier merkt man also wenig von den Änderungen. Am Wochenende habe ich oft ca 180+ Km offene Autobahn. Hier schaffe ich es nur selten den Fuß von Gas zu lassen und bewege mich meist über 230 km/h Tacho.

I have never seen those moondiscs, they are effective and look cool.

Impressive results. It is interesting that you didn't sell the car, in the modded state for more. I would consider your use case to be quite beneficial to many.

Beautifull and eco 👍👍

nice video, quite instructive... i think that I might have, maybe, installed a fan topush some air through the exhaust system 'tunnel', maybe hooked to the switch for the radiator fan, so that it would provide a small airflow in that exhaust tunnel, whenever the car's radiator needed air, normally when stopped, so that you wouldn't overheat rustproofing paint/wax, sound absorption, or interior mat materials...but, hey, just an idea, cheap, efficient, easy, and just that extra bit of margin for safety...

Very interesting.

It's coll that when I look at my 2015 Polo TDI, and compare it to my 2002 Golf Variant TDI, I see lots of elements that are similar to this video. No wonder the thing is so frugal if I drive slowly.

so cool

Impressive project. Also cool thing you mentioned that you removed the mods before selling to avoid fire hazard for the next owner.

There’s a guy in like Oregon or Washington in the USA who claims to have gotten an old F250 over 25mpg (would have been like 15mpg or worse normally) with similar ideas. Covered all the undercarriage with plates, built a custom lid for his bed that was aero, put in a button starter so he would never idle, removed the a/c and a whole bunch of other parts to drop weight. The truck was functional but not really as a truck anymore. It’s funny because he could have just started with a car that got better mileage, like in this case.

Cool Video! Makes me thinking about a flat underbody for Ma Corolla

I really like little projects like this, well thought out! I have a California van with the 110kW TDI engine, my best mod to spare fuel is to accelerate easy and never go beyond 110kph; on long trips on flat land it takes about 6.5L/100km, these days in a more mountainous area and ith short trips I'm at around 7.8 combined sadly, and I don't see any easy legal mods I could do to lower that.

This is real hypermiling 👏🏻👏🏻👏🏻

great video :)

It would be amazing if you could make tests like - fuel consumption with moon disks, fuel consumption with foam, fuel consumption with lower springs, fuel consumption with new tires, fuel consumption with plates under the car... etc We would have a hint with what we should begin with :) I have a Honda Fit/Jazz from 2003 and I would love to make some improvements...

Great video! If only the standard customer would have just a little technical understanding, manufacturers wouldn’t need to oversize most components. Cars would be cheaper, lighter and more aero.

You can get similar gains in fuel efficiency by other means (depending on the car). for example, I used to hae a 1072 Triumph Dolomite 1850 with a 4 speed manyal gearbox. In these cars the exhaust is particularly restrictive, so I replaced it with a rally spec exhaust and downpipe. Nothing else was done and average fuel economy improved from 30 mpg to 36mpg (UK gallons) and there was a modest improvement in performance. The other case ws on a 244 Volvo (B21A engine and 4 speen manual gearbox. I knew the car would need a new clutch soon, so with the help of the 240 specialist in the Volvo enthusiasts club, I also replaced the gearbox with an Overdrive one (0.67 overdrive) at rhe same time as the new clutch. Again nothing else was changed. this time fuel ecinomy improved from an average of 28mpg to 34mpg. Granted these would probably have cost more than in this VW's case (A custom rally exhaust and downpipe is NOT cheap, neither is an overdrive gearbosx an a new clutch) but the results were just as wotrh rthe expense as I kept these two cars for another 5 years or so.

Spitze!

Another thing you could do if you are good with any bondo or other body work materials is cover the unused vents to create a smooth surface this would further reduce drag you could even install a small diffuser that will increase some down force but should also create less drag if you want to goto the extreme remove the door handles and once again smooth it out with something else just maybe have a latch underneath to get in next you could have vents coming from above or on the side next to wheel well to reduce the air tumble caused from the tire and extract it out the side further reducing drag and adding some cooling another thing you could do is add a vent somewhere along the hood to reduce the pressure and heat under the hood

Very, very interesting. Thank you! I would be curious about how much each individual modification made to the efficiency improvements, though. Nice work.

I expected some Vortex Generators before watching. We tried a VG geometry similar to Airtab's VG's in our universities Shell Eco-marathon/Efficiency Challenge car and it was promising in CFD. But had to pause the project because we didn't have any time left for Wind Tunnel/flow-vis/cotton thread testing before the competition.

Subscribed a couple of weeks ago and this channel allready feels like a gem. I can't wait for it to blow up but keep the honest interest trait of it and the fascination for the engineering parts, please

Nice video, where do you get the obersize wheelcovers from?

Very interesting. “I’m a quick driver”. Best way to reduce fuel consumption with *no work at all* is slow down 😂. Changing driving style is the the single most effective way of reducing fuel consumption. I have a W220 S320 Mercedes. During recent fuel shortages because of strikes in France I reduced my average consumption by 15% (down from 8.6l/100km to 7.3) just by driving at 70 instead of 85 in an 80 limit and 100 instead of 115 in a 110 limit and accelerating more gently and planning ahead better. At the time everyone was driving more slowly and more carefully for the same reason. It didn’t even impact journey times significantly. I very regularly use my car for the same 105-km journey. Typical journey times roughly went from 1h12m to 1h20m. As you say use case is also important. It’s a great argument for taking driving away from drivers and putting it in the hands of AI; robots would do the job far better…