[CCS1]

I am new to this forum. I have just ordered a brand new 330xd Touring in Arctic grey without roof rails but I have been in two minds to call the dealer and add them before it is too late. I think it looks sleek without them but maybe a bit naked as 90 percent have them.

I have read some postings here on the subject but a friend told me not to bother as not only do they cost money but the addition of roof rails adds to drag, weight and increases fuel consumption, possibly substantially.

Right enough, according to an article I found online, this is the case (see link below).

Does anyone know how badly the new Touring’s roof rails affect drag and fuel consumption?

many thanks

http://www.whatcar.co.uk/news-specia...563&EL=3171330

[Ghunger]

Hmm, 15% sounds excessive for roof rails, though I don't have any proof either way. I'm fairly confident that the rails will hurt your fuel economy, how much, is not a simple question though. I personally like the look of the touring without the rails and unless I was planning on hauling large items that would require the rails I'd remove them, or possibly look into an aftermarket system that could be added or removed as needed.

[Phila]

On another note, i was wondering if the add on roof rails / skii racks for the 3 series sedans are easy to install and remove. I kinda want roof racks for the winter season but I'd also like to be able to take them off when I don't need them. Is that possible and easy to do?

[JSpira]

Originally Posted by Philasan

On another note, i was wondering if the add on roof rails / skii racks for the 3 series sedans are easy to install and remove. I kinda want roof racks for the winter season but I'd also like to be able to take them off when I don't need them. Is that possible and easy to do?

Yes, very easy.

[ward]

proper tire inflation is way more of a factor than roof rails


also, the summer sport pack tires (if you option them) probably make more of an aero difference than the roof rails


it's a non issue from an economy standpoint, if you need them get them

[Hotan Braskey]

I can't imagine that roof rails would make a significant difference on fuel consumption. If you were traveling a very long distance (like cross country) at a high sustained speed, then the rails may make a small difference, but in everyday mixed driving, I wouls think they would be a non-factor.

[CCS1]

Thanks very much for the opinions which are much appreciated.

I will stick without but I suppose the sedan roof rack from BMW can be fitted, should I need to carry stuff later on. Can anyone confirm this?

[Dante]

Originally Posted by CCS1

Thanks very much for the opinions which are much appreciated.

I will stick without but I suppose the sedan roof rack from BMW can be fitted, should I need to carry stuff later on. Can anyone confirm this?

Hi CCS1, welcome to the forums!

I was giving me a hard time about adding the roof rails, too. But after taking some pictures, which you can find here, and seeing some better equipped cars including one with M package without the rails, I decided on ordering them.

I think it looks kind of naked, especially from behind. Also the shark fin (navigation antenna) looks a bit of out place without the rails.

I think an increase in fuel consumption of 15% would only occur with a full rack mounted, not only the rails.

But anyway, looking forward to seeing pics of your car!

Do you mind sharing more specs of your car? Options? Wheels?

[gos]

Originally Posted by Dante

I think an increase in fuel consumption of 15% would only occur with a full rack mounted, not only the rails.

Wife's WRX has rails, onto which we mount a Yakima rack. We don't have any fairing for the rack setup.

When driving with nothing on the rails, she gets about 28mpg.
Adding the empty rack gets her to about 25 mpg.
With two bikes on the rack, it's about 24 mpg in normal driving.

Hardly scientific, but I don't think the rails themselves would hurt much aerodynamically. I'm sure they design the shapes of the rails using wind tunnel data, etc.

[mjh93sa]

At the risk of putting you all to sleep....

The roof rails aren't going to make that much of a difference. To put it in perspective, compare the differences between a UK spec. 318iSE in saloon and touring forms. I've picked this as it's low powered enough that it runs out of puff before any silly speed limiter

Weight of the Touring is up by 5% from 1435 to 1505kg.
Drag coefficient rises from 0.27 to 0.29, up 7.4%.
Vmax is 129mph for the saloon and 128mph for the tourer - nuffin in it.
0-62mph is 10.0 for the saloon and 10.4 for the Touring - but that'll be the weight telling.
The 50-75mph times are identical.
Fuel consumption for the Tourer is worse by 2.5% at 34.9mpg compared to 35.8 for the saloon.

Drag is related to the square of velocity and also related the frontal area of the body moving through the air, so in comparison to the rest of the car the roof rails are not going to make a huge difference. What will make a big difference is if you mount any crossbars to the roofrails. At that point you will dramatically increase drag and noise through increased frontal area and turbulent airflow. Whilst the Touring has a higher drag coefficient, the biggest difference is hauling the extra weight.

Estate cars can actually be quite aerodynamic as the long flat section of the roof promotes smooth airflow along the length of the car. The tailgate then gives a sharp, abrupt cutoff so that the air is able to cleanly seperate from the car. A saloon on the otherhand must be carefully designed to avoid turbulent airflow from the end of the roof. If you look at the bootlid you'll also notice that the saloon will generally a nice sharp line for the air to seperate from. This is more noticable on the E46 where this line overhangs the back of the car (and even more so on the M3CSL ducktail).

You can really see aerodynamics at work when you have a really clean well waxed car that's been rained on. As you increase speed you'll see all the flow patterns as the water runs off, including the turbulent flow on the rear screen. I've even had lumps of ice slide off the roof and then slide around in circles on the back screen where the turbulence of the air coming off the roof promotes a couple of vortices.

[Dante]

Originally Posted by OilBurner

At the risk of putting you all to sleep....

The roof rails aren't going to make that much of a difference. To put it in perspective, compare the differences between a UK spec. 318iSE in saloon and touring forms. I've picked this as it's low powered enough that it runs out of puff before any silly speed limiter

Weight of the Touring is up by 5% from 1435 to 1505kg.
Drag coefficient rises from 0.27 to 0.29, up 7.4%.
Vmax is 129mph for the saloon and 128mph for the tourer - nuffin in it.
0-62mph is 10.0 for the saloon and 10.4 for the Touring - but that'll be the weight telling.
The 50-75mph times are identical.
Fuel consumption for the Tourer is worse by 2.5% at 34.9mpg compared to 35.8 for the saloon.

Drag is related to the square of velocity and also related the frontal area of the body moving through the air, so in comparison to the rest of the car the roof rails are not going to make a huge difference. What will make a big difference is if you mount any crossbars to the roofrails. At that point you will dramatically increase drag and noise through increased frontal area and turbulent airflow. Whilst the Touring has a higher drag coefficient, the biggest difference is hauling the extra weight.

Estate cars can actually be quite aerodynamic as the long flat section of the roof promotes smooth airflow along the length of the car. The tailgate then gives a sharp, abrupt cutoff so that the air is able to cleanly seperate from the car. A saloon on the otherhand must be carefully designed to avoid turbulent airflow from the end of the roof. If you look at the bootlid you'll also notice that the saloon will generally a nice sharp line for the air to seperate from. This is more noticable on the E46 where this line overhangs the back of the car (and even more so on the M3CSL ducktail).

You can really see aerodynamics at work when you have a really clean well waxed car that's been rained on. As you increase speed you'll see all the flow patterns as the water runs off, including the turbulent flow on the rear screen. I've even had lumps of ice slide off the roof and then slide around in circles on the back screen where the turbulence of the air coming off the roof promotes a couple of vortices.

Thanks for that!

[CCS1]

Thanks everyone for super input. This is a great site with knowledgable and helpful members.

Thanks too to Dante for taking an interest in the spec of my new car which is due in October.

With so many E91s on the road, I wanted to make mine a bit unique within my budget, naturally.

Artic with no roof rails but with dark tinted rear windows and the 21 spoke 17 inch wheels model 160 is the look I am going for. As it is the 4x4 330xd, the suspension is only set at the normal not lower height which I also prefer anyway.

I have taken the xenon lights with obligatory lamp washers, retractable ext. mirrors, park distance control F/R and rain/light sensors. Inside I have taken the boot pack, half leather seats in black and one or two other minor extras. I have kept the titan metal finish inside because the sports steering wheel I am also taking is finished in titan too, and this looks better than the alu finish with black steering wheel IMHO. The 330xd has a good level of standard eq. too as I am sure you know better than me. No sat/nav however, but I am very pleased with the tomtom we have at the moment, so that should do the trick.

cheers.

[Dante]

Originally Posted by CCS1

Thanks everyone for super input. This is a great site with knowledgable and helpful members.

Thanks too to Dante for taking an interest in the spec of my new car which is due in October.

With so many E91s on the road, I wanted to make mine a bit unique within my budget, naturally.

Artic with no roof rails but with dark tinted rear windows and the 21 spoke 17 inch wheels model 160 is the look I am going for. As it is the 4x4 330xd, the suspension is only set at the normal not lower height which I also prefer anyway.

I have taken the xenon lights with obligatory lamp washers, retractable ext. mirrors, park distance control F/R and rain/light sensors. Inside I have taken the boot pack, half leather seats in black and one or two other minor extras. I have kept the titan metal finish inside because the sports steering wheel I am also taking is finished in titan too, and this looks better than the alu finish with black steering wheel IMHO. The 330xd has a good level of standard eq. too as I am sure you know better than me. No sat/nav however, but I am very pleased with the tomtom we have at the moment, so that should do the trick.

cheers.

Nice!

And now the wait...

[gIzzE]

Personally I think the tourings look naked without the rails, but the 3 does look better than most.

The rails do not add drag and kill your mpg, the rails you add on however do, the ones the run across, this will make your mpg around 10% worse with the bare rails and around 15% worse if you have a cycle carrier or similar attached.

[cidair]

Excellent thread!!!

These roof rails has been haunting me too.
I have finally decided to go WITH the rails!
Personally I think it looks naked without ( or? )! Hard decision anyway.

CCS1:

Congrats on an excellent car choice

[cidair]

My friend had a 330Xi E46 without rails. It looked very sporty but somehow naked for a touring.

Maybe it´s a hard decision because I want a sporty car but the touring is actually not sporty by design?

[CCS1]

Thanks everyone.

One question for Cidair. You say that you have ordered a 2007 model 330xd Touring, due for delivery this year. Like you, I am also in Europe.

I ordered my 330xd touring late June (earlier than accidentally implied in my opening post) with a delivery date of beginning of October 2006.

I asked if it would be the latest model and the dealer told me that there was nothing to worry about as the E91 was only launched in late 2005 so it was a new model.

My question is: will I get the 2007 model and what is the difference between the 2006 and 2007 model so I am informed before checking with my dealer?

Many thanks for any help.

[lux.sh]

roof rack is not a brick wall above your roof. its not going to make a big difference...

[cidair]

Originally Posted by CCS1

Thanks everyone.

One question for Cidair. You say that you have ordered a 2007 model 330xd Touring, due for delivery this year. Like you, I am also in Europe.

I ordered my 330xd touring late June (earlier than accidentally implied in my opening post) with a delivery date of beginning of October 2006.

I asked if it would be the latest model and the dealer told me that there was nothing to worry about as the E91 was only launched in late 2005 so it was a new model.

My question is: will I get the 2007 model and what is the difference between the 2006 and 2007 model so I am informed before checking with my dealer?

Many thanks for any help.

That seems like a very long time between order and delivery?

Anyway, there are actually no modelyears in Europe anymore. It´s the production date that counts. But, people are still talking about which model year you have and ,as far as I know, if your car is produced September or later it will be a 2007 model. If you ask your dealer for the new pricelist, it will be effective from September 1st, and include some new options like headlight assist!

[ahnh77]

another question..i have the bmw bar on my e90 xi sedan....i like to get a thule snowboard carrier....but where can i buy the attachment for the bmw bars for thule?....i looked at different pieces that came with the universal snowboard carrier..but none seem to be a match for the bmw bars....

[18LLC]

roof rail adding weight to your car???? i am 208lbs, and i am adding weight to my car, should i drive my car without sitting in it?

[ahnh77]

the only thing i notice with the roof racks is the added wind noise...when you drive with your windows down on the freeway