Remember, it's not how fast the limo was moving, it's what the limo's speed was reduced to in terms of frame count. Such as the following:
zframe 168-z171 was entered as a distance of .9ft traveled.
Extend that over 1 second of time:
18.3/3 = 6.1 x .9ft = 5.49ft traveled
30ft distance via the diorama / 5.49ft per sec = 5.464sec duration
5.464sec x 18.3frames per sec = 100 frames
while:
zframe161-166 was also entered as a distance of .9ft
Extended over 1 sec:
18.3/5 =3.66 .9ft = 3.294ft traveled
30ft distance via the diorama /3.294ft per sec = 9.107...sec
9.107..sec x 18.3 frames per sec = 166.66... frames