How many shots do you take of each car?
Between 2 and 6 on average, however the reasons for doing so will vary depending on a number of things.
Not sure if giving a 'sucking eggs' lesson, but for general interest I'll try to cover some of the basics.
Firstly, I'll generally set the camera up the same way, I'll set the aperture as low/big as possible for the lens (as you zoom the aperture will get smaller, but will always stay at the lowest possible unless you've set it higher). I'll set the exposure time to somewhere between 1/100th and 1/400th depending on conditions, distance to subject (and how much that my change during the pass). And then I'll tweak the ISO as necessary to get the exposure right.
Let's say you're at 1/320 exposure time, this means you can only take a third of the number of photos than someone shooting in sports mode a 1/1000 (for example). Realistically you'll get more than a couple of seconds to shoot a passing car, so you have the time to recentre the camera on the target*, and press the shutter release separately - which depending on the settings allows the camera to refocus, and re-metre properly** - and you'll still get a few photos to choose from.
* I don't like image stabilisation on my big lens because at the point you've reached a half click on the shutter release, and the metering starts, the IS kicks in - this disconnects your movement from what you're seeing in the viewfinder and it can give you a big 'wobble'.
** I've said I use full manual, so the metering isn't doing anything but feeding back info to the exposure bar in the bottom of the view finder, it can be a pain, but if you've got a car emerging from under a canopy of trees or passing from shade to light, it's pretty important to be adjusting this as you go.
The second biggest factor at Goodwood is trackside obstructions. There's a lot of flag poles, there's a lot of Tannoy poles, there's marshalls, there's umbrellas, there's grandstand stantions - there's a lot of places (mostly infront of the house), where it's virtually impossible to get a car length in frame without something getting in the way, unless you're right up to the bales. In these circumstances, a lot of the time all you can do is click and hope - the more photos the more chance of getting a clean shot. In the photo of the white Mustang Boss 329, you can see there's a pole of some sort slap bang down the middle of the car. It's possible to lessen how obvious it is, by increasing the exposure time, and hoping it disappears into motion blur - that photo was at 1/100, and the obstruction is tolerable, but getting a halfway crisp image of something moving at speed at 1/100 is unlikely.
Just getting it in focus and not blurred comes with practice, but again, the more shots you take, it's likely the more chance you'll get something desirable.
If I know the exposure is right, and the framing is easy, and there won't be obstructions, I'll perhaps just take 2 shots, because it's just more to scroll past on the SD card otherwise.
Ultimately at an event, I'll take 500-1000 photos a day, and generally there's not more than 10 or 20 I'd class as good photos, most I just post for interest, rather than for artistic merit.
Once issue with DSLR is that once you get accustomed to a big phone screen to use as a view finder or to see the end result, the tiny screen on the DSLR looks pixilated and gives you little confidence in the photo not being blurry or out of focus.
The screen on my EOS60 is only 3 inch and about 1 megapixel. It's certainly not state of the art, but allows for a very quick zoom in on the preview, and it only takes a moment to see if it's a sharp image or not. It is still a problem, and sometimes I'll go to an image afterwards that I thought was pinsharp only to be disappointed, but at that point there's nothing you can really do about it whatever you're shooting with.
I have confidence that when the focus point in my viewfinder glows, and the camera beeps, I'll get a 95% sharp image (though obviously I can still have messed up the framing and exposure)... on a phone camera, I'm not even sure if it's taken the photo or not!
However if you are shooting from a fixed location and of objects that will be at the same distance away, it’s a case of doing a few test shoots and then sticking with the settings that work.
Yeah, generally the first 10 shots or so I'll still be tweaking stuff, then after that you've largely nailed the settings, and can start thinking about framing the shot, and tilt, and stuff like that. A good example of one of my favourite locations for taking photos is at Brands Hatch, on the infield at Druids, you're largely at the centre point for the radius the car is following, and it's close enough that you can do it with a compact lens, it's great for practicing panning technique.
For what it's worth, the EXIF data should be public on all my Flickr photos in all the albums, so you can see what my favoured settings are, and what type of lens are used for what photos.
I have to say, I like to move about a lot. At Goodwood you get a batch of cars go up, then come back down. That gap does allow you to move on to the next location, though like I say, half of the hill is wiped out by trackside obstructions, and on the Saturday and the Sunday, you get hemmed in whilst in the Grandstands very quickly, other spots with a decent vantage point, and no obstructions are few and far between.
