Audi A2 1.2 TDI 2001

[hege]

Thanks for pointing it out. You are right, the rear track is approx 2.3 inches (60 mm) narrower than the front and I tried my best to take it into consideration. The narrower rear track does explain why the car does not want to go straight while driving in deep snow.

Aligning worn suspensions is not a very rewarding task, so I did not try very hard. Trying to measure long distances alone with a tape ruler also isn't super accurate. There is an old saying that the weight of the car takes out the slack in the suspension.

[Vekke]

On winter the fuel consumption rises about half a liter in these 3l machines, the cold starts are the main reason and not so good winter tire options the seconds cause.

Have you already studied this:
Session 4 - 1 - Hussain Ali - Drag Reduction on a Production Vehicle

[hege]

Yes I have. It is very interesting. They started with Cd 0.288 and I'm wondering how low they could have got if they had started with a 3L model with Cd 0.25.

Also your post on another A2 from Finland has been inspirational: http://ecomodder.com/forum/showthrea...-fe-26651.html
Not to mention your Lupo.

I like the rear box cavity idea. I tried to measure how long the box is, and by measuring the side of the rear spoiler I got 6" is exactly the bed size length the 3d-printer I use. I would love to have something real to 3d-print to keep my motivation up when learning how to use the printer.

I already have some aluminium sheet waiting for me to get motivated on making the flat underbody. Maybe next summer when it gets warmer.

[hege]

I have been updating the fuel log. Yesterday I did my best trip so far. 100 km in heavy tailwind with average consumption of 2.6 L/100 km according to the computer.

This winter fuel consumption has been 3.6 L/100 km on average (66 mpg). It takes a really long time for the engine to warm up so fuel consumption is very high in the beginning.

The grille block is the only mod this far. Next weekend I'll change to summer tires and hopefully the pumps will start soon selling summer diesel which has higher energy content.

[hege]

I got to the top of the ecomodder diesel top 10 with 72.3 MPG average for the last 90 days.



I did the second mod to the car, removed mud flaps.

[Daox]

Congrats, very nice mileage!

[hege]

Reading about Vekke’s A8 1.2 tdi got me browsing through spritmonitor site to see fuel consumption figures that car users report. I’m not happy that my consumption average with the A2 has been 68.2 mpg (US), (3.4 L/100 km), and in comparison the best reported lifetime average is 89.0 mpg (US) (2.64 L/100 km) Übersicht: Audi - A2 - Spritmonitor.de

This far I’ve only made small mods to the car, and I guess it’s time to stop whining and stop being lazy on my part. Hopefully I will be having the time to make modifications to the car and other things in life won’t interfer to much.

On the mechanical side I think the engine is not reaching operating temperature and the stock temp gauge is useless in showing temperature. It is digital and points always at 90 deg C. I just ordered a scangauge to be able to monitor temperatures better. The intercooler air flow is blocked at the moment, and it might cause some trouble that I’m not aware of. Might be that the ECU is correcting for high intake temps by increasing fueling. Also the wheel angles need to be checked with real equipment.

The aerodynamic side is more interesting. Luckily the A2 has been part of many aerodynamic studies, so I won’t need to guess how much each modification affects drag.



A table with the same modifications tested in two different wind tunnels, S2A and MIRA.
Source: Sustainable Vehicle Technologies (IMechE, Woodhead Publishing) https://books.google.fi/books?id=g_t...epage&q&f=true



A picture of the standard and final configuration. Same source as above.

What was interesting according to the source:
“One unusual feature of the A2 was the negligible drag reduction resulting from reduced ground clearance. There is an almost universal ‘rule of thumb’ which states that drag coefficient increases by ΔCd = 0.004 for every 10 mm of ride height. This rule did not apply to the A2”

And.

“Although some effort was spent modifying the upper body shape, including a larger backlight spoiler, no improvements were made, suggesting that the side profile, in particular, was well optimised”



I think the above picture is from models that they tried to test to improve the upper shape. I have seen these pictures in a couple sources, and now I understand why the improvement of the modifications has never been told. Source of picture: http://www2.warwick.ac.uk/fac/sci/wm...view_may11.pdf



In the Sustanable Vehicle Technologies the effect of each modification made in the study by Hussain Ali is quantified. I'm always happy to see numbers instead of just a graph.



The original study by Hussain Ali. Vekke linked it above, but I’ll link the source again because it’s connected to the above picture. Session 4 - 1 - Hussain Ali - Drag Reduction on a Production Vehicle

Seems like the post became long, and now I forgot what I was really going to write about.
I don't know how much I'll modify the car yet. I'll start by adjusting the intakes when I get the scangauge and next I'll be making the underbody flat and installing smaller mirrors. I'm happy about the information that I don't necessarily need to lower the car to make it more aero, because I need the ground clearance especially in winter time.

[hege]

Originally Posted by hege

I forgot what I was really going to write about.

Now I remembered. This summer I did a three week 4 835.5 mile (7782 km) trip around Europe. The car worked great and average fuel consumption was 69 mpg (3.4 L/100km). I didn't drive very economically. Especially Italy was the worst for fuel consumption. Serpentine roads with loads of hills and slow speed driving..

Had to remove the grill block in the alps because temperatures started to rise. But I could drive at speed of 80 mph (130 km/h) in 99 deg F without the temperature needle starting to rise. On the autobahn I also tested how fast I could go, and in slight tailwind and steep downhill I got 119.3 mph (192 km/h) according to the GPS. Fuel consumption according to the DIS was 38 mpg (6.2 L/100km). A 105-112 mph (170-180 km/h) speed was sustainable. It feels very stable at speed, at 100 mph (160 km/h) it grabs the wind and goes like an arrow. Side winds make the car steer into the wind, so it doesn't feel scary even in heavy winds.

I did a record tank driving through Denmark in heavy tail wind, 93 mpg (2.53 L / 100km). The first 200 km was in heavy tail wind, and according the DIS the consumption was 124 mpg (1.9 L /100 km) in a speed of 55 mph (90 km/h). The wind changed and rest of the tank was in side wind so I couldn't keep the consumption low.

I did miss air conditioning. When we started it was 99 deg F (37 deg C) and when we got back it was 102 deg F (39 deg C).

[Vekke]

Nice ,you should check your cam timing. That effects to fuel consumption quite much.

[hege]

Thanks for the tip. Didn't even think of doing that. I have the locking tools for 1.9 TDI engine and I guess this is the same procedure, and just checking the timing should be easy.

I guess everything should be checked on this car.

Summer vacation just ended, and this morning the traffic flow to work was awesome. 94 mpg (2.5 L/100 km) to work according to DIS. Previous best was 84 mpg (2.8 L/100km).