Anybody used a roof box?
Discussion
Has anyone any experience of using a roof box on their EV, and how catastrophic it was on range?
Already have an oldish Halfords box that doesn't look like the most aero focused thing, but haven't bought any bars for the current car.
Car is a Model 3 LR, but concern is that smallish battery and French autoroute speeds will potentially mean we start to curse the thing after a thousand miles or so then be stuck with it!
Already have an oldish Halfords box that doesn't look like the most aero focused thing, but haven't bought any bars for the current car.
Car is a Model 3 LR, but concern is that smallish battery and French autoroute speeds will potentially mean we start to curse the thing after a thousand miles or so then be stuck with it!
A quick calc suggests that a typical roofbox has about 10% the cross-sectional area of a Model 3.
Assuming it's similarly streamlined, the drag should also be about 10% of the car, so you're increasing drag by that much, plus a bit more for the roof bars supporting it, maybe another 5% for those ?
I had a kayak on my Polestar 2, unfortunately I haven't driven enough to really get a comparative range, but I reckon it was in the ballpark of 15-20% higher consumption.
Assuming it's similarly streamlined, the drag should also be about 10% of the car, so you're increasing drag by that much, plus a bit more for the roof bars supporting it, maybe another 5% for those ?
I had a kayak on my Polestar 2, unfortunately I haven't driven enough to really get a comparative range, but I reckon it was in the ballpark of 15-20% higher consumption.
Appreciate all the responses.
Really doesn’t sound as terrible as I was expecting then.
I’m also going to be travelling with an infant so I’m going to be stopping more than either the car or we need to anyway.
My last use of roof bars had a pair of bikes on the roof of a 400bhp petrol, worked it out afterwards that it would have been cheaper to hire bikes on location than take them!
Really doesn’t sound as terrible as I was expecting then.
I’m also going to be travelling with an infant so I’m going to be stopping more than either the car or we need to anyway.
My last use of roof bars had a pair of bikes on the roof of a 400bhp petrol, worked it out afterwards that it would have been cheaper to hire bikes on location than take them!
I have one (well I borrow the box but have bars) for my iX3.
First time using the box on this car at Christmas and on the way to our holiday the range impact wasn t terrible considering it was cold but Google maps took me along a lot of 50mph country lanes to avoid traffic which minimised the impact with lower speeds and regen for the corners etc.
On the way back was all dual carriageways and motorways and the range plummeted. I had to do a cheeky splash and dash charge while stopping for a toddler wee stop to ensure I had enough to get home.
We are talking estimated 150 mile total range loaded up with luggage, child, dog and roof box. As I said though it s winter so range is probably 190-210 on a good day with no passengers.
However it s only once or twice a year maximum we do this so can tolerate it.
I ve noticed if we have gone away without dog (so similar luggage but with no roof box) then range impact is negligible - it will still do 230-240 miles on a summers steady constant run instead of 260ish on my own so the box does make a bit of a dent.
First time using the box on this car at Christmas and on the way to our holiday the range impact wasn t terrible considering it was cold but Google maps took me along a lot of 50mph country lanes to avoid traffic which minimised the impact with lower speeds and regen for the corners etc.
On the way back was all dual carriageways and motorways and the range plummeted. I had to do a cheeky splash and dash charge while stopping for a toddler wee stop to ensure I had enough to get home.
We are talking estimated 150 mile total range loaded up with luggage, child, dog and roof box. As I said though it s winter so range is probably 190-210 on a good day with no passengers.
However it s only once or twice a year maximum we do this so can tolerate it.
I ve noticed if we have gone away without dog (so similar luggage but with no roof box) then range impact is negligible - it will still do 230-240 miles on a summers steady constant run instead of 260ish on my own so the box does make a bit of a dent.
We always use a roof box when on long trips. We have the slippery low-profile one from 2021, supplied by Volvo. I think it was actually a rebranded Thule, and it was on offer with the bars for around £400.00, which is nuts, as they look like they are over £1000.00 now just for the box.
It does make a difference, especially at 80mph in France, but not as much as you would think.
That said, the Polestar was a bit of a brick, so something more streamlined might make it more noticeable.
It does make a difference, especially at 80mph in France, but not as much as you would think.
That said, the Polestar was a bit of a brick, so something more streamlined might make it more noticeable.
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