I agree that they definitely need to add a manual transmission. for a big reason, its that the automatic transmission in NFS 2015 tends to shift at random times and usually too early. to get the best speed i would need to shift at 7500rpm yet the auto trans keeps shifting at 5000rpm. and when you take a corner to drift it on most cars either it downshifts too much and just revs all day and the car stops drifting, or it up-shifts and then the car doesn't have enough power to keep the drift. most times it just shifts twice it goes from 3rd to 5th. this would be a very easy fix if they would add a manual transmission. also id rather have manual not only for those reasons but when cruising instead with the auto you would cruise at say 50mph at 6000rpm but id rather cruise at lower rpms like 3500rpms.
in my opinion i would put the change camera view and engine off to the left dpad buttons and put up shift and downshift on the right button layout.
i use a PS4 so my up-shift would be X the downshift would be Square, e-brake O and nos Triangle. but this should be interchangeable.