Runlength has nothing to do with distance between cars. I really have no idea what that does since I have found no reason to mess with it. What you are looking for is in the dummies NIF. This is a bit of a touchy item, so take your time at it.
First, copy the two dummies for the Auto Car and rename them to match your new car. If you are using the original for the V1, leave that one alone. On to the V2.
Open the NIF and click on line 6. Go down to Block Details and make note of the value of Y in the Translation line, about halfway down. It's -106.1577
Go up and click on line 7 and make note of the Y again, -72.7699. I should note here that line 6 is the coupler point where it hooks up to the next car, in the back in this case. Line 7 is the pivot point for the truck, again, the rear in this case.
The difference between the two is 33.3878. This number is NOT the same for all cars, and in some cases, this number is not the same for the rear and front. Go figure
I'll let you get the numbers for the front yourself.
Now, go to your car itself. In it you will find b_wheel_01 thru b_wheel_04. These are the axle points. Halfway between them is the pivot point. You're looking at the X in this case. b_wheel_01 has a value of 89.8660, and b_wheel_02 has a value of 55.9709. The algebra formula we are looking for is W01+((W01-W02)/2). In laymen terms, subtract b_wheel_02 form b_wheel_01, (33.8951) divide that by 2 (16.9475) and add that to b_wheel_02 (72.9184).
If you look up at line 7 you will see that the numbers are close. Line 9, the front pivot point, is 73.0307, which is even closer. Ignore the negative, that is of no concern here.
Go and do the calculations on your new Autorack and come back.
Ok, this is where the dummies numbers come in. Take the number you got from your calculation and put a negative of it in line 7, the Y in Translation. Put a positive in the same place in line 9.
Now take the numbers you got in subtracting the pivot from the hookup and adjust those two numbers. Be sure to get the positive and negative correct. This will give you a base to test with.
From here on, any adjustments you do with the hookup values, do it equally to the front and back. While adjusting only one will look OK for a string on these cars, it may not look right if other cars are connected.
Now that I've totally confused you

, take two aspirin, have a cup of coffee

, stay away from the liquor

, and feel free to question me

.....nicely.