Fuel consumption & Roof Racks

Submitted: Thursday, Sep 04, 2003 at 11:15
ThreadID: 7032 Views:13532 Replies:11 FollowUps:15
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I am after some first hand accounts of anyone who has actually measured the difference in fuel consumption between having roof racks on or off.

I have an ARB Roof rack with wind deflector fitted and I seem to be getting no where nere the "claimed"figures others seem to be getting with similar models.

I changed to larger tyres, fitted the roof rack, and had the injector pump overhauled at the same time so I don't know if any on e thing has caused a change in fuel economy.

I am talking about driving with the rack empty. I know there will be an effect when loaded so I am not interested in that. What I after is anyones exprience , will alter say 5mpg 20% ETC.

i GUESS I could take the rack off and find out if it is the rack but they are just so damn heavy plus I am going away again shortly.We have so little time to enjoy our land
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Reply By: Truckster (Vic) - Thursday, Sep 04, 2003 at 11:22

Thursday, Sep 04, 2003 at 11:22
I just rigged up a pully off the shed roof, 10 mins it was off and hanging up...

Well worth it. Took 1 roll of nylon rope and 4 large hook things from Mitre 10. They are heavy aint they!

I didnt measure the difference as in MPG, but I know I got more klms to work without it on than with it. Also the speed difference is very measured.
AnswerID: 30084

Follow Up By: Member - Glenn(VIC) - Thursday, Sep 04, 2003 at 11:30

Thursday, Sep 04, 2003 at 11:30
Hi Truckster,

Do you have a photo of the pulley set up? I would be interested as I am thinking of the same type of setup when I purchase my rook rack.

CheersJust Do It!

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FollowupID: 21153

Follow Up By: Truckster (Vic) - Thursday, Sep 04, 2003 at 11:34

Thursday, Sep 04, 2003 at 11:34
No photos, it was just throw a rope over the beams, I was going to get the roller pulley things, but hey Im a tightarse ;)

then pull the rack up 1 side at a time, then the hooks were around 1/2inch thick, and big enough to go round a 5x3beam.

Took no time, and well worth it.
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FollowupID: 21154

Follow Up By: Paul from Roof Rack World - Sunday, Sep 14, 2003 at 11:10

Sunday, Sep 14, 2003 at 11:10
Have a look at the Thule Box lift. Is rated to 100kg and is $182
Paul.......from Thule Car Racks.
link text
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FollowupID: 21970

Follow Up By: Paul from Roof Rack World - Sunday, Sep 14, 2003 at 11:12

Sunday, Sep 14, 2003 at 11:12
Opps...sorry..look here.....
www.thuleracks.com/thule/product.asp?dept_id=15&sku=571
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FollowupID: 21971

Reply By: Member - Rohan K - Thursday, Sep 04, 2003 at 12:16

Thursday, Sep 04, 2003 at 12:16
David, after a recent trip that returned worse fuel economy than expected, I experimented with and without the rack (empty and with wind deflector). I reckon it has added about 1 litre/100 kms, or roughly 6 to 7 %.Smile, you're on ExplorOz
Rohan (Sydney - on the QLD side of the Harbour Bridge)
AnswerID: 30086

Reply By: Voxson (Adelaide) - Thursday, Sep 04, 2003 at 13:46

Thursday, Sep 04, 2003 at 13:46
I measured NO difference at all between the two but i had a patrol with 4.2 efi which was over 20 litres per 100klm no matter how i was set up...._____________________________________________

_____________________________________________
AnswerID: 30094

Follow Up By: windypops - Thursday, Sep 04, 2003 at 14:07

Thursday, Sep 04, 2003 at 14:07
Geeeeez. 20 litres per 100 kms. That is appalling. Have you got a concrete left foot or is the car out of tune? My nana gets better economy out of her monster truck with tripple Arias 600 cubic inche blown motors.

Should have bought a TOYOTA

Oh what a fuel bill !!!!!!!!!!!!!!!!
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Follow Up By: Outnabout David (SA) - Thursday, Sep 04, 2003 at 14:39

Thursday, Sep 04, 2003 at 14:39
Windypops,
A lot of the old 100# petrol sixes are only getting that. That is why they have gone V8 on the facelift.We have so little time to enjoy our land
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FollowupID: 21161

Follow Up By: Chris (W.A.) - Sunday, Sep 07, 2003 at 12:32

Sunday, Sep 07, 2003 at 12:32
Hi Dave,
I found that with my roofrack it doesn't make much difference when empty but once the equipment goes higher than the spoiler it tends to change. I think I've removed my rack twice since 1999 (to give roof a polish)

I always get about 20L/100km but once the racks loaded I have to sacrifice speed and usually have to sit on about 95 - 100kms/h on the highway to lessen the wind resistance and get same economy. If not it goes up to about 23L/100kms.
Obviously it doesn't matter much once offroad as you're not going fast enough for wind resistance to come into it.

RegardsGibb River in July.
Chris
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Reply By: CC - Thursday, Sep 04, 2003 at 14:17

Thursday, Sep 04, 2003 at 14:17
I have a Hilux Surf with Thule Roof Racks (the rounded ones instead of the square edge ones). It's the 1KZ-TE turbo diesel with Intercooler (same as the current Prado). I measure the L/100km every time I fill up and I couldn't find any noticeable difference to the figures that I had before I put them on a few months back. So I just keep them on the roof permanently.

Also, there is absolutely no wind noise at all coming from the roof, even when driven up to 120km/h or so.

In July I went up to Mt Buller (VIC) for a snow trip. With 4 people on board, a full load of luggage, plus skis in a ski bag on the roof rack, the fuel economy was 9.8L/100km !! That's including going up the mountain and down (probably 10km to go up the winding road to the top and them another 10km back down).

If the cross bars on your roof rack are the rounded ones, they should be OK. But at least I know Thule is excellent.
AnswerID: 30099

Follow Up By: Outnabout David (SA) - Thursday, Sep 04, 2003 at 14:45

Thursday, Sep 04, 2003 at 14:45
CC,

I would kill to get that economy. I have a turbo Diesel Prado going up the Freeway to the hills and back every day and only getting 14.8 - 15.
with all the changes I did I reckon I have dropped 10-20%. I think think I am overfuelling but I need to eliminate things before I go back to the pump repairer.

I love to know fuel economy from anyone with an old model Turbo Diesel Prado AUTO. We have so little time to enjoy our land
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FollowupID: 21163

Follow Up By: Martin - Friday, Sep 05, 2003 at 08:40

Friday, Sep 05, 2003 at 08:40
David for comparison, I have a new Prado TD Auto. I check each fill (at about 1500kms so it's usually a mix of suburbs, freeway and country) Mainly open road is 11l/100, mainly town is 12 l/100. It hasn't been outside that range yet. Very happy by the way as my petrol model gives 15-16l/100 around town and 12.5 13.5l/100 on highway.
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FollowupID: 21225

Reply By: diamond (bendigo) - Thursday, Sep 04, 2003 at 18:02

Thursday, Sep 04, 2003 at 18:02
gday david.
with out roof rack we get about 370-400ks to 90ltr of gas gq.
with racks we lose about 50ks to a tank.
thats empty when im to slack to remove it.
now that its opf im to slack to put it back on so just make stuff fit in car lol—~‘¬‘¥•s’B
AnswerID: 30120

Follow Up By: Martin - Friday, Sep 05, 2003 at 08:48

Friday, Sep 05, 2003 at 08:48
Diamond, that's surprisingly poor economy and makes me wonder if gas is worth ever considering! Your figures for with racks are 28.125l/100. In my TD Prado I get 12l/100 maximum. That makes gas 2.3 times less economical. Take into account the installation and current gas versus diesel price and there's no value to me even considering it in future. Initial diesel purchase price was same as petrol by the way so i'm saving from day 1.
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FollowupID: 21226

Follow Up By: Luke - Friday, Sep 05, 2003 at 09:28

Friday, Sep 05, 2003 at 09:28
How much is Deisel these days? around 90c/lt?

Gas is around 30c/lt.....................

...and if you have a TD Prado - why would you be considering gas?

:-)
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FollowupID: 21228

Follow Up By: diamond (bendigo) - Friday, Sep 05, 2003 at 20:19

Friday, Sep 05, 2003 at 20:19
gday martin.
works out to about 22ltr/100 with out rack on gas
petrol about 16ltr/100
gas 35cpl x 22 ltr is $7.70 per 100ks .
petrol 90cplx16ltr is$14.40per 100ks.
nearly half the cost—~‘¬‘¥•s’B
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FollowupID: 21271

Follow Up By: phil - Friday, Sep 05, 2003 at 22:05

Friday, Sep 05, 2003 at 22:05
Gas is 54 c/litre here in the New England (Armidale)
Makes rather a difference from 33!
Phil
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FollowupID: 21283

Follow Up By: Martin - Saturday, Sep 06, 2003 at 00:15

Saturday, Sep 06, 2003 at 00:15
Hello Diamond, I only worked it out on the figures you gave - they were 320km from 90 litres (your worst case scenario) and that comes to 28.125l/100.
Luke, I haven't paid more than 78.5 for diesel (Safeway 82.5 less 4c/litre) and I have noticed that it doesn't rise and fall with the other fuel prices. Note the price fromphil above. I was interested in the gas option because I like to look further ahead than "tomorrow" and I always consider my options. I buy a new 4wd every 9-10 months.
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FollowupID: 21290

Follow Up By: Martin - Saturday, Sep 06, 2003 at 00:27

Saturday, Sep 06, 2003 at 00:27
Just had a quick look at the fuel prices on this site. Gas is not available at many of the towns listed and in many cases when it is available it's well over half the price of diesel. Just doesn't seem a good option on those figures combined with much shorter range and shorter engine life, but that's just my opinion and I'm interested in the opinions of others. Is there anybody out there who is a serious four wheel driver (long hauls in remote areas etc) who uses gas. Has anyone done the CSR on gas for example and if so how did it go?
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FollowupID: 21292

Reply By: Hilly - Thursday, Sep 04, 2003 at 18:24

Thursday, Sep 04, 2003 at 18:24
My ex Cruiser and new Patrol seem to lose 1 km per litre with the rack on. Down from about 7km to the litre to 6 ish.

Hilly
AnswerID: 30126

Reply By: Member - Howard- Thursday, Sep 04, 2003 at 20:40

Thursday, Sep 04, 2003 at 20:40
I've got a 80 series petrol 1fzfe and have run a roof rack full time for the last 50,000km why ? without rack 5.17 km/litre ,with 5.00km/litre
hell thats 19/100km v 20/100 km for the technically correct .
above figures are empty running
same roof rack on old 60 series diesel went from 4litres/100 into a headwind thru central QLD with tinny on roof to 10km /litre on OTR to cape loaded to hilt . all depends on how hard(read fast) you want to push into the wind.
for a couple of bucks a week IMHO why go to the effort of removing /reinstalling with inherent storage prob to save stuff all.
Howard
AnswerID: 30142

Reply By: GUPatrol - Friday, Sep 05, 2003 at 09:25

Friday, Sep 05, 2003 at 09:25
I have a GU 4.2TD, the roofrack is an ARB full lenght.

My fuel economy without the rack is about 11.5 to 12 L in 100kms.

The roof rack increases fuel usage by 2 litres per 100kms on the highway and 1 L per 100kms in the city (with some highway driving).

I too made up a pulley system at home but the ARB rack is very heavy so rope was not enough.
I used a boat winch attached to the wall with a pulley on the steel beam, even the square (1 inch diameter) steel beam warps when its pulling the rack!

I only put the rack on when I absolutely need it, ie: long trips that require an extra spare etc.
Will
AnswerID: 30192

Reply By: Luke - Friday, Sep 05, 2003 at 09:31

Friday, Sep 05, 2003 at 09:31
G'day David,

I had the alloy TJM roof rack on my GU2.8lt TDI Patrol.

No wind deflector up front.

Wind noise and drag was significant, and fuel consumption worsened by 2-3 litres per 100 kilometres.

Great roof rack though :-)

Cheers,

Luke.
AnswerID: 30193

Reply By: Member - Andrew(WA) - Friday, Sep 05, 2003 at 23:48

Friday, Sep 05, 2003 at 23:48
Reading through the replies to your question, no one has commented on the larger tyres you say you have fitted.

How much bigger are they? Bigger tyres will generally cost you more in fuel because they are 1. heavier 2. the engine has more resistance from the road to push against.

Constant highway use may see a slight improvement in economy over smaller tyres but when you knock it all together..city...country....off road, I think it is safe to say you would use a bit more fuel with the bigger tyres. Especially in stop start situations where the engine has to work that little bit harder everytime you take off.

I have seen similar comments in previous threads.

Just a thought.

cheers
AnswerID: 30236

Reply By: Warpig - Tuesday, Sep 30, 2003 at 17:59

Tuesday, Sep 30, 2003 at 17:59
I have several tens of thousands of kilometers worth of fuel consumption data for a HZJ75 troopcarrier, with and without roof racks, and with roofrack plus a 3.5 m tinny. The differences the various roof attachments make to fuel consumption is trivial compared to driving, road and wind conditions. So unless you are travelling around at 120 km/h or so, the roof rack may not the major cause of your fuel consumption 'problem'. I suggest that the tyres might be worth looking at, as some of the others have done.
AnswerID: 32412

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