Reduction in range - roof box/bike

[markharro]

We are hoping to drive to France later this month. Has anyone got experience driving long distance with a roof box fitted? If so how much range does it sap? Same for (probably) one roof mounted bike although we may forgo that and hire. Thanks

 

[markharro]

Someone surely must having experience using a roof box on a MS?

 

[Jason71]

there are M3 tests that might give you an idea:

 

[markharro]

Thats really helpful thanks.

 

[nikhon]

Woah, I've been contemplating buying roof racks and a box for my MS...and after watching that test by Bjorn I don't want to risk it at all. That's crazy.

 

[henleyregatta]

I cannot answer for the roof box because I've not tried it with our Model S.

I can say that putting 4 x bikes on the roof results in a 33% loss of range even when speed is kept to 60MPH. And I know this because we took our car in this configuration around Northern France a couple of summers ago.

The practical effect of this is that you can't skip as many superchargers on your route as you would have otherwise. Since they all seem to be in hotel car parks close to areas of shopping, tourism or food, this is very little inconvenience at all

(In case you're wondering, the Aero roof bars alone have negligible effect on range - at most 2-3% - but I regretted leaving the 4 x bike racks mounted as, even without any bikes, I lost about 15% range at 70MPH as well as incurring a lot of noise).

I would expect a suitably aerodynamic roof box to be between 20-30% range loss based on these experiences.

 

[Jason71]

I cannot answer for the roof box because I've not tried it with our Model S.

I can say that putting 4 x bikes on the roof results in a 33% loss of range even when speed is kept to 60MPH. And I know this because we took our car in this configuration around Northern France a couple of summers ago.

The practical effect of this is that you can't skip as many superchargers on your route as you would have otherwise. Since they all seem to be in hotel car parks close to areas of shopping, tourism or food, this is very little inconvenience at all

(In case you're wondering, the Aero roof bars alone have negligible effect on range - at most 2-3% - but I regretted leaving the 4 x bike racks mounted as, even without any bikes, I lost about 15% range at 70MPH as well as incurring a lot of noise).

I would expect a suitably aerodynamic roof box to be between 20-30% range loss based on these experiences.

I the impact of drag on energy consumption has a squared relationship with speed so around town you would notice very little impact. motorway journeys will be exponentially worse. Sadly that is of course the sort of driving people are more likely to do with things on the roof. Not much need for 4 bikes on a trip to Tesco.

 

[MrBadger]

Roofbox doesn't seem to affect aero

Darkside of the Plume

(c) Project Plume Greenpower Racing: PROJECT PLUME RACING

 

[nikhon]

Wondering if a tow bar platform & box combo would be alot better for long journeys

 

[Avendit]

I think I saw a video (no link, sorry) that said put the roof box on backwards for better aero? Also going back to my days of ICE and investigating this, I believe that its as much dependent on the weight you put in the box, as hauling that around has almost as big an impact as the aero, depending on your speed.

bikes on the roof is adding a lot of complicated shapes and a big frontal area so will have a big impact.

Personal experience with 4 bikes on the back of my 3, and the seats down and interior absolutely rammed, cost me 10% range and going at exactly the speed limit through a mix of 50/60/70 roads (I normally default to +5 and overtakes etc as required). So actual cost is significantly more than the 10%. Would have been worse with more 70 - going over 60 had an appreciable impact on the amount of right foot I needed.

 

[sclo]

We quite regularly have 3 mountain bikes on the roof, with front wheels removed, depending on conditions it adds 25-30% around 70mph. If you are are in strong winds or rain expect the impact to be significantly more. That said, due to the drag vs speed if you drop down towards 60 it becomes much much better, add in an HGV or tall transit and its not too bad. If you use ABRP a setting of 450 seems to give a reasonable estimate that you can bet with some slipstreaming

 

[gt2690b]

We quite regularly have 3 mountain bikes on the roof, with front wheels removed, depending on conditions it adds 25-30% around 70mph. If you are are in strong winds or rain expect the impact to be significantly more. That said, due to the drag vs speed if you drop down towards 60 it becomes much much better, add in an HGV or tall transit and its not too bad. If you use ABRP a setting of 450 seems to give a reasonable estimate that you can bet with some slipstreaming

450 wh/mi??? thats way more than 25-30%

 

[kuruma]

I would expect a suitably aerodynamic roof box to be between 20-30% range loss based on these experiences.

Last summer on our first couple of long-range trips with our Motion XT Thule roof box on our M3, we didn't notice any significant hit on range at our normal cruising speed of 60mph on motorways.

 

[init6]

The OP went to France almost two years ago. Pretty sure they'll already have their answer

 

[Llama.]

I have a medium Thule roof box and notice that my energy consumption goes from abet of about 245 wh/m to 275 wh/m at 70mph in my M3 LR.

On long journeys I find this is not enough of a difference to make any noticeable impact on where or how frequently I stop to charge.

Perhaps I end up arriving at chargers with 27% charge vs 30% charge.

But who cares really. There are Tesla chargers everywhere in Europe Just put your roof box of there and go. Won’t make any real difference.

Have fun