How in the world do you manage the workflow to sort through 1k to 2k photos? Any tips on your technique/work flow are very mush appreciated.
Both, are you utilizing multiply focus points or an Individual ?
I use FastRawViewer, which very quickly does a basic render of all the raw images and has a very fast reject system (shift+command+delete) that moves rejects into a reject subfolder, which you can later delete. At slow shutter speeds there are many blurred shots so you can quickly reject them, bang, bang, bang. Also FRV can be set to clearly show clipped highlights, underexposure and poor focus, so any like that are also quickly rejected. That leaves a greatly reduced number that you can consider more closely and choose for proper rendering.
I use a single focus point, usually the centre one as it is most accurate (dual cross-type on my 80D) and I usually want the front of the car near the centre of the image so it has space to 'drive' into in the image. Often I prefocus where I know the car will be when I take the photo and that works well. Usually you are at a small aperture with such slow shutter speeds, so the deep DOF will ensure you get good focus on the car or bike.