If you google Rhino Racks and Thule (pronounced Tool'e or Tooley) that should give you some info Terry. (Edit: Links added)

http://www.thule.com.au/ 

http://www.rhinorack.com.au/products/luggage-carriers

I have just bought Rhino bars with a Thule roof pod, I did like the look of some of the roof trays though, some had a wind deflector on the front (see the Rhino site). I decided against them as I will only be carrying light stuff and I prefer it to be out of site when parked in towns etc and also better protection from the weather etc. The roof trays will carry a much heavier load though, but the load rating of the roof bars need to be taken into account (some add a third one in the middle, mine only has two).

The shop people told me that you will get some wind resistance with the bars but very little, although the roof trays apparently make a fair bit of noise compared to the pods according to them. You will get some fuel use increase and he said better to remove pods and baskets (roof trays) when not in use. On one of the sites I looked at it had a pod on one side of the roof bars and a narrow basket on the other.

Here is a pic of mine, Rhino bars and Thule pod, the side rails were already on the vehicle;

-- Edited by Duh on Sunday 10th of November 2013 03:32:04 PM

-- Edited by Duh on Sunday 10th of November 2013 03:38:49 PM

No matter what shape you put up there it will create resistance.
Some streamlining shapes offer less resistance than others. But you still have to drag that silhouette/cross section through the air.
I dont think I have ever seen any comparison figures for these items. Be interesting to see what comes up.

I try to keep the roof bars empty when doing long journeys. Even a shovel strapped up there adds to the fuel consumption.

Duh wrote:

---

Do you remove the cross bars too Ellie and Mike or leave them on there when you remove anything on them?  Do they make a noise or use some fuel as well?

The chap I spoke to did say they would use some on their own but it is minimal.   The luggage carriers and pods though did give an noticeable increase according to him, and the luggage carriers and trays made more wind noise than the pods. 

---

 I now have an Awning on the Isuzu Dmax so the wing bars and awning are there sort of permanently.   As we use the Dmax specifically for trips away.  

Coincidentally I took them all off  the Dmax yesterday,      as I had noticed a fixing fault in the awning attachment to the wing bar.   They had used the wrong fixing bolt and it was damaging the wingbar   "T"  track.    

   Actually it does not take long to get the awning and wing bars off the roof.

Having done it once I think 30 mins from whoa to finish stored in the garage would be about right.

Thanks for the feedback Ellie and Mike, everything has a calculated price if you want to use it (eg; airconditioning on the move) I am happy to have my additions for the purpose I had them fitted and of course as you said remove what you don't need when you are not using them.

Interesting about the nose cone Cultana, I was wondering what they were, thanks for the link.

I knew fuel consumption did rise at a certain point Wombat280 and thanks for details.   Tyre wear will also increase at higher speeds too according to the experts.

Caravan and Motorhome magazine did a write up on the nose cone some time ago and gave it e thumbs-up. Was mounted on an old Millard and hinged up to access front windows. Its main benefit was that I held the van steadier when being overtaken by semi-trailers because of better airflow around van frontal area.

Peter