08-22-2009, 01:20 PM
Hey ppl :)
The weather here was very hot lately (temperature between 30 to 36ºC) but great to hypermiling a bit ;)
On my daily commute, the best so far was 3.2l/100Km on a 42Km trip from work back to home, but the usually is around 3.5l/100Km
But on the opposite way, it's very difficult to do below 4l/100Km...Maybe is because the crosswind on the Highway :( is a 16Km bridge (on the other hand, the wind helps me to cruise on the highway, but when I go home :p)
The commute is 19Km on Highway and 23Km is on Country - roads
In this tank I have on my odometer 850Km and 4l/100Km on the BC and still 5 fuels light's left...maybe I can break my record on a single tank (so far I made 1050Km on a tank)
What can I do to minimize the crosswind effect on my HCH?
08-22-2009, 05:28 PM
You are doing great!!
For those in NA, here's a quick conversion:
3.2 L/100km = 73.5 MPG US
3.5 L/100km = 67.2 MPG US
4.0 L/100km = 58.8 MPG US
BTW: There's a pretty good chance your actual FE will be better than the displayed ;)
Regarding crosswinds: Other than avoiding certain paths, I have no idea on how to make the car less vulnerable to the effects of crosswinds without a redesign of the exterior shape of the car.
Do you have the "pie plate" wheels by any chance as we do in North America?... or is your car equipped with the typical Euro/JDM "sport" rims?
08-23-2009, 12:36 PM
My HCH have the “pie plate” wheels :) you can chose between them or the “sport” rims :D but I bought used, so I didn’t have the opportunity to chose.
I have an alternative commute…is a bit longer (more 7Km and all the way is most on Highway), but I have pay the toll twice :mad:, it have more traffic coming (but no stopping because most people are on vacation on these month).
The god thing is it’s easier to me to break bellow 4l/100Km…maybe the terrain is better for that happening.
08-23-2009, 01:14 PM
Your question got me to thinking about the sailing course I took years ago. The "apparent wind" is the resultant force of the actual wind and the "headwind" from the car's forward motion. The faster you drive the more the apparent wind moves toward the front of the car. Therefore the car's speed will affect the wind resistance much the same as with no crosswind. Also, the push from the side will increase the steering correction you need to make. Again, much like a sail boat must overcome the sideways slip when heading towards the wind. Therefore, I would think slowing down when you experience strong cross or head winds will help.
Remember that wind resistance increases with the square of the car speed plus the actual headwind. Therefore, as an example, driving at 100 Km/h into a 20 Km/h headwind is like driving at 120 Km/h and this will result in 44% greater wind resistance than if there was no wind at all.
In effect it's possible the wind is increasing your fuel consumption by, say, .3 L/100 km going one way and reducing it about the same amount going in the other direction.
Some other factors to consider:
Are the uphill grades about equal? Steeper grades increase your fuel consumtption more than gradual grades even if the elevation change is the same.
Your morning trip will be with a colder start and cooler air temperature than in the afternoon.
As Msantos said, you are doing great. I have a hard time getting below 4.0 L/100 km.
Years ago, my wife and I drove the highway from Lisbon south to the Algarve and I remember the very long bridge you refer to. Wonderful trip and many fond memories!
08-23-2009, 02:20 PM
I wish I could find the article I read online once about auto aerodynamics and wind. Design and testing are done to minimize drag from airflow coming from the front because (a) that's the only way they can do it - factoring in crosswinds would be extremely complex if not unmanageable theoretically, and (b) at higher speeds where drag becomes increasingly important, the airflow from the front due to the car's motion will tend to dominate all but the strongest crosswinds.
BUT crosswinds can still disturb the airflow over the car and contribute to drag, and at lower speeds (say 40mph) a stiff (say 25mph) crosswind becomes significant.
This is one way car aerodynamics differs from aero for airplanes: planes are immersed in the air and thus never have "crosswinds" that affect airflow over the plane's surfaces.