Let me try to clarify this.
Shooting anything in bright sunlight leaves us with decisions to make.
We can opt to use no flash at all, we can use low powered flashguns to add a litle light in places, we can add reflectors to direct "spare" light into shadow areas or we can take control of he lighting by using extremely powerful portable lighting - different people have different approaches and although sometimes there is clearly a right or wrong approach, in many cases there isn't, there is just the approach used by that particular photographer in that situation, either because it suited his/rer style or resources.
Nobody can really advise on just how much power is needed. It's possible to work to some kind of a formulae, e.g. the "sunny 16" rule, which says that in direct summer sunlight, at 1/200th second, the correct exposure from the sun will be f/11 @ 100 ISO, so any flash lighti9ng that in any way overpowers the sun must be sufficient to require an aperture smaller than f/11 - but that doesn't help much because it's all down to the inverse square law, i.e. to how far the light from the flash has to travel before reaching the subject.
Here's a tutorial I did, with example shots and also showing the setup.
I took thee shots with the Safari 2 on the 1st July last year, basically to demonstrate that the Safari 2 can be used in the rain. It turned out to be the hottest day of the year and there was no rain
It didn't matter because the Safari 2 had more than enough power to overcome this problem, and of course we made our own rain. I did this because I could and because I had to, but someone doing it just for fun could have just come back on a dull rainy day. As it happens, I didn't need to use anywhere near the full power of the flash, this is because although it was brilliant sunshine, the flash only had to travel a tiny distance. I think, although I can't be sure after all this time, that the power of the flash was only set to about 1/8th power. But the "rain" (superbly created by Phil V)
was rimlit (it wouldn't have shown up without the rimlighting) and I'm pretty sure that the Safari 2 that provided that lighting was not only at full power, but also had a high intensity reflector fitted that dramatically enhanced that power.
If you're going to photograph items as big as cars then you need far more power. We have several professional car photographers who use the Safari system, and most of them have several units often totalling between 2,400 and 4,800 Ws - this is because they have to get the work done regardless of the weather but as Richard pointed out earlier, if you have the option of shooting in the dark or on a dull day, it gets a lot easier.
And cars are difficult, not only because they're big, they're also very shiny, they require massive silks or softboxes to create diffused specular highlights. Nearly all modern car photographers get around these problems by shooting just small sections of the car and comping them together later, in fact their work requires very good Photoshop skills and
a lot of time spent in front of the computer.
