VW Touareg 3500 kg trailertowing machine

[teoman]

Those are impressive numbers.

[Vekke]

Today 6.1-6.2 l/100km @ 100 km/h at 50 km distance at litlle bit more flat roads. Looking good. Weather was +18 celsius which helped little bit also.

[Vekke]

Fuel consumption at the moment 5.7l/100km @ 100 km/h avg speed
https://youtu.be/RKx5m-eE2cA
Current mod list:
Mods:
- lowering springs
- Installed smooth undertray (whole underside)
- flat hubcaps
- grill block
- tire front air defletors
- Rear muffler removed
- Tire pressures to sidewall max which is 3,8 bar at the moment
- my own ecu remap program


Acceleration with the new custom chip:

https://www.youtube.com/watch?v=8K0xdi04xMU

[Vekke]

Before changing tires I have installed a kammback spoiler which helped about 5%. So I have already seen 5.5-5.6 l/100km @ 100 km/h figures. Then I had 225/60R16 Hakkapeliitta R winter tires which had 4mm thread depth left.https://ecomodder.com/forum/tool-aer...ToStep=40-65-1

At the moment struggling still struggling with tires. Bougth 205/75R16 113/111S Nokian Hakka C2 tires, but fuel consumption increased 0,5 liters :/. Their figures were rolling resistance C, rain grip C and noise 70db. Rolling resistance in between (RRC6,8-8,0) Migth be due to these are new so rolling resistance is 20% higher than with those very worn winter tires. Also winter tires RRC is measured at. Here calculated at rrc 8.0. I also lose 2% on smaller diameter, which you need to add on top of that. https://ecomodder.com/forum/tool-aer...ToStep=40-65-1 Its a little shame as these tires were really nice to drive even with 5 bar pressures.

Now trying to find a better solution. and found this Continental VanContact Eco 235/65 R16C 115/113R they have A, A and 71 db C2 tyre class. Which means their rollign resistance RRC is under 5,5!. Note that passenger tire (c1 tyre) A level means only under 6,5 RRC. So these are 15% better in rolling resistance than the A level tires for passenger cars C1 tyres. Their load index 115 = 1215kg means they can carry a big load. This also means they are tested with heavy loads on the RRC tests, which should lead better rolling characteristics on the touareg where one corner weigths about 550kg.

Well now the fuel consumption starts to look much better, at least on paper . 5.3 liters should be on reach @ 100 km/h speed. https://ecomodder.com/forum/tool-aer...ToStep=40-65-1 With the C tires you can also put much higher tire pressures as max sidewall is 5,2 bars usually.

EDIT: In reality these new Continental VanContact Eco 235/65 R16C 115/113R tires are only slightly better than the previous Nokians. Fuel consumption about 5,9-6,0 liters at 100 km/h speed

One option to test will also be 265/50R19 Nokian WR SUV 3, which is also AA tire, but its tested on winter temps so rrc is under 6.5, but actually it is lower on summer. These I try to find used ones to get even lower rollign resistance figures. 10 celsius change in tire temperature means 20% reduction in rolling resistance.

As you can see from those calculations the heavier the car the bigger effect on rolling resistance has on your fuel consumption. On tiny cars the aerodynamics play maybe bigger role what I have learned so far.

[teoman]

What is the city consumption?

[Vekke]

Tested tires savonlinna route 100km:
Measured fuel consumption @ 100km/h gps speed/ speedo error/ trip error/ corrected values/tire model
235/65R17 6,2/2%/ 0%/6,2l Nokian hakkapeliitta 7 suv 6mm thread left 3,5 bar, studs removed (no hubcaps)
205/75R16 C 6,1/5,28%/3,28%/6,3l Nokian Hakka C2 205/75 R16C 113/111S, new tires 5,0 bar
225/70R16 5,6/4,2%/2,2%/5,72l Nokian Hakkapeliitta R 225/70R16 4mm thread left, 3,5 bar

Tested tires Lappeenranta route 51km:
235/65R17 5,9/2%/ 0%/5,9l Nokian hakkapeliitta 7 suv 6mm thread left 3,5 bar, studs removed (no hubcaps) temp 26,5 celsius

235/65R17 5,8/2%/ 0%/5,8l Nokian hakkapeliitta 7 suv 6mm thread left 3,5 bar, studs removed (with hubcaps) temp 24,5 celsius
Hubcab effect 1,7% with touareg oem 17" wheels. Hubcabs did not fill the whole wheel.

235/65R16C 5,7/5,77%/3,57%/5,9l Continental VanContact Eco 235/65 R16C 115/113R (with hubcaps) plus new mirrors and smoother upper grill block temp +18 celsius

235/65R16C 5,7/5,77%/3,57%/5,9l Continental VanContact Eco 235/65 R16C 115/113R (with hubcaps) plus new mirrors and smoother upper grill block. Siped my tires to halve the pattern. temp +14,5 celsius 5 m/s sidewind, Parks ligths on

235/65R16C 5,6/5,77%/3,57%/5,8l Continental VanContact Eco 235/65 R16C 115/113R (with hubcaps) plus new mirrors and smoother upper grill block. Siped my tires to halve the pattern. temp +15 celsius 3 m/s sidewind.

235/65R16C 5,5/5,77%/3,57%/5,7l Continental VanContact Eco 235/65 R16C 115/113R (with hubcaps) plus new mirrors and smoother upper grill block. Siped my tires to halve the pattern Adjusted rear front tire deflectors. temp +21 celsius 3 m/s sidewind

235/65R16C 5,5/5,77%/3,57%/5,7l Continental VanContact Eco 235/65 R16C 115/113R (with hubcaps) plus new mirrors and smoother upper grill block. Siped my tires to halve the pattern Adjusted rear front tire deflectors. Put on front lower A-arm plastics, smoothed front bumber lower parts and adjusted front tire deflectors. temp +21 celsius 3 m/s tailwind. Was wet road for 5km distance which dropped tyre temps in halfway of the test.

235/65R16C 5,4/5,77%/3,57%/5,6l Continental VanContact Eco 235/65 R16C 115/113R (with hubcaps) plus new mirrors and smoother upper grill block. Siped my tires to halve the pattern Adjusted rear front tire deflectors. Put on front lower A-arm plastics, smoothed front bumber lower parts and adjusted front tire deflectors. temp +22 celsius 2 m/s sidewind. Cutted smaller the rear tire deflectors heigth to about 60mm from body.

Tail/headwinds are worse for fuel economy than sidewinds based on my own testing. Reason is that max speed is increased more on headwinds that increace the fuel consumption more than what you gain by going "slower" on tailwinds.

[Vekke]

https://youtu.be/E_OsWefoYjU getting closer to target

[teoman]

That is indeed a tiny modification to be gettin 0.1L.