its also because of the chasis codes as well. (r31, r32, r33, r34) = skyline gtr, g35 chasis code is v35 hence they called it only skyline. they didnt think calling it a gtr would be proper. the new one they didnt call it a skyline due to it might cause confusions with the g35. it is rumored that the chasis code for the new gtr will be r35 which is more fitting for it.