When I tested it, the HDR was not as good at bright areas of the image as the other modes so if a license plate was in the headlight beam then it did not do so well. I believe all the other modes use WDR although the documentation doesn't say so. Both WDR and HDR combine multiple exposures to produce the final image, I came to the conclusion that the WDR was doing a better job of merging the exposures. HDR is different, it is done in the image sensor instead of in the processor, I guess it might give better battery life but I haven't tested it.
45fps is an advantage if you want to watch the video in slow motion and you have decent lighting conditions. For normal use, there are less bits per frame and so you loose a bit of quality in return for the faster update rate. 45fps / 60fps will not give less motion blur than 30fps in any camera as the exposure times will be the same, it is just the time gap between frames that is different, also in the dark when exposures longer than 1/60th or 1/45th second are needed to collect enough light the 60fps and 45fps modes will switch to taking 30fps and recording each frame as two identical frames to create the 60fps or duplicating every other frame to create the 45fps. On playback the result becomes identical to 30 fps in low light.
The best mode is 2560x1080 since that is the mode with the highest resolution, it is also the mode with the narrowest field of view so you have a bit of zoom in addition to the extra pixels, the two together will give you the most readable license plates, it is also the only mode with no scaling from sensor resolution thus gives a clean image with no scaling distortions.
