No Dave, I’m correct.  Yes, longitude in the geographical sense involves a dimension east or west of the prime meridian, and that’s the SECOND definition, but as you say in the first meaning, it’s “running lengthwise.”  As we all know (?) the B end of the car is the back end, the A end, the front.  From this you establish which is the left side and which is the right side, confirmed on many cars with an “L” or “R” painted on the side near the door.

So my understanding is standing at the B end of the car, right side to the right, left side to the left and what is ahead of me is the length of the car, the first definition from the Oxford dictionary.

If you’re looking at this in comparison to the geographical use of longitude and latitude, the East/West lines run across the car, from side to side.  Don’t say “left to right,” as the lines go either way..

Schuyler