Roof Box and reduction of range

[f1eng]

Drag and hence the effect on range is proportional to speed squared so the effect of adding something to the roof will be very dependant on speed as well as the frontal area and drag coefficient of the addition.
A bike standing up on top of the car will probably produce more drag than a well designed roof box, though I haven't wind tunnel tested a road car in 40 years...

On a long journey at high cruising speed they will both be pretty bad, I expect.

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[jvincent]

Drag and hence the effect on range is proportional to speed squared so the effect of adding something to the roof will be very dependant on speed as well as the frontal area and drag coefficient of the addition.

So buy a roof box and slow down! 70 instead of 85 might make the increased drag more manageable. We're going on vacation, right? ?

 

[Swissbob]

And slightly better on the way back… 130kmh in Austria 120kmh in Switzerland. A couple of stops and a fair bit of traffic reduced average speed. The roof box is a non issue for range.

 

[thecoloradokid]

And slightly better on the way back… 130kmh in Austria 120kmh in Switzerland. A couple of stops and a fair bit of traffic reduced average speed. The roof box is a non issue for range.


Bob, you may feel it was a non issue for range because you averaged 40 miles an hour!!!!! That is like driving around in your neigborhood.

Double that speed and think your opinion will change.

 

[Swissbob]

you might be surprised what your average speed looks like after a couple of charging stops and rush hour traffic jams. I can assure you I wasn’t driving at 40mph on the motorway ?

 

[Scandinavian]

We’re on holiday in Austria with roof box. This is the journey here from Switzerland with full roof box at highway speeds. It’s the new aero Roofbox. Only 10-15% down on normal consumption

I am very impressed with how low your consumption is with a Roof box. I have not been able to get so low figures over the last couple of weeks without a roof box. And that is with a Taycan sedan. I guess I might be paying the price for the 21 inch wheels now that it gets colder??

Variety of driving on motorways at 110 km/h and lots of 70 km/h plus traffic in town.

 

[McgR]

Why do you keep using the word 'autonomy'? I think you're asking the wrong question.

In French this is the word used for range. Maybe OP is from the French speaking part of Canada?

And slightly better on the way back… 130kmh in Austria 120kmh in Switzerland. A couple of stops and a fair bit of traffic reduced average speed. The roof box is a non issue for range.

did you get these figures driving most of the trip on the highway 120-130 km/h? In my current car the average speed is calculated with the car is switched on and not departure and arrival time. Does the Taycan also take the charging time to calculated the average speed.

It still is quite warm. Probably will be worse in winter.

 

[McgR]

It must be a very well designed roof box. I wonder if they quote the drag factor?
[/QUOTEI think this is the new performance roof box. It is specifically designed for the Taycan and can handle speeds up to 200 km/h where apparently other roof boxes only allow 130 km/h. I wouldn't be interested in driving 200 km/h with the roofbox on a road trip but it would interest me if aerodynamics of this roof box would reduce the range reduction compared to other models.

 

[Swissbob]

did you get these figures driving most of the trip on the highway 120-130 km/h? In my current car the average speed is calculated with the car is switched on and not departure and arrival time. Does the Taycan also take the charging time to calculated the average speed.

It still is quite warm. Probably will be worse in winter.

Yep it’s mainly “highways” 120kph in CH, 130kph in Austria. There are several 100/110 sections, a few non highway sections and also a few traffic jams where we were at a standstill for a while eg around Zürich hence the lower average speed.

The temperature makes a bigger difference. Starting cold in Austria and driving up some mountain passes with temps around zero the consumption was much higher. But these were shorter journeys so range anxiety not an issue. There were also some 22KW chargers in the ski resort car parks which were handy (if pricey compared with Ionity).

 

[Swissbob]

Good place for a road trip ?

 

[McgR]

Yep it’s mainly “highways” 120kph in CH, 130kph in Austria. There are several 100/110 sections, a few non highway sections and also a few traffic jams where we were at a standstill for a while eg around Zürich hence the lower average speed.

The temperature makes a bigger difference. Starting cold in Austria and driving up some mountain passes with temps around zero the consumption was much higher. But these were shorter journeys so range anxiety not an issue. There were also some 22KW chargers in the ski resort car parks which were handy (if pricey compared with Ionity).

this summer I drove from Galtur 16 km up the silvretta hoch alpenstrasse with my X5 45e. I used half of my 20 kWh battery. This is half the range I could have done on the highways. Going up Mountain roads is terrible for the range. Fortunately a lot is recuperated driving down again.

 

[Midlifecrisis]

Good place for a road trip ?

Now I see why you have the roof box. The 2 smallest children had to go somewhere!

 

[WoKe]

I was still contemplating to get the (rearmounted) bike-rack and mount some sort of box like the Thule backspace or one of the competing brands that even have a foldable version made of tarp.
But seeing the (very) limited impact on range I'll just go for the roof crossbars and use the roofbox I already have (Thule Motion XT XL 500 liter box).
It actually looks a lot like the Porsche 'optimized' one so don't think I'll lose a lot of range compared to theirs.

 

[McgR]

I was still contemplating to get the (rearmounted) bike-rack and mount some sort of box like the Thule backspace or one of the competing brands that even have a foldable version made of tarp.
But seeing the (very) limited impact on range I'll just go for the roof crossbars and use the roofbox I already have (Thule Motion XT XL 500 liter box).
It actually looks a lot like the Porsche 'optimized' one so don't think I'll lose a lot of range compared to theirs.

Just out of curiosity, are you keeping the XC 90 for holiday trips? My wife has a car similar as your XC40 and it is too small for road trips. Th only thing that I am worried about is the holiday trips. And buying a XC60 T6/8 is a bit to much

 

[WoKe]

Just out of curiosity, are you keeping the XC 90 for holiday trips? My wife has a car similar as your XC40 and it is too small for road trips. Th only thing that I am worried about is the holiday trips. And buying a XC60 T6/8 is a bit to much

We replaced a Countryman SE Hybrid with the electric Volvo XC40, and the Taycan CT4S will replace the XC90. We only use the full luggage capacity twice a year. Winter holiday and summer holiday. I'm not going to size for the exception, so when we need to take a bit more luggage we'll use a roofbox and just add a charging stop or lunch to the trip (or take the plane, drop a kid in friends car, ...)

And if you really need a bigger car for 1 or 2 weeks ... just rent one ;-)
I actually prefer a rental when on holidays, less stress ...

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