Dougbetsy,
I don't know about the Army, but in the AF, when they attend training they are on orders, thus they pay for the airfare. DS did FT which I assume is the equivalent of LDAC. The AF picked up the entire dime, plus paid him TDY pay for the weeks he was at Maxwell.
I am surprised that the Army pays per diem for a 23 mile trip. In the AD world, per diem is only paid if you must spend 8 hours away from your station. When you PCS, they actually calculate how many days according to them that it takes to get from 1 place to another. 23 miles would not be considered valid reasons to pay per diem. If I recall they expect 400 miles to be completed for per diem. They would also pay per diem if you had to fly.
The last time we PCS'd the mileage was 38 cents per mile for the AD member, 37 cents for dependent #1, and 18 cents for every dependent after that, plus reimbursement for gas and tolls with receipts. Again that is AD, not ROTC, so the rules could be different. In your cases none of you have dependents.
Out of curiosity did they give you a weight allowance too? If they did and you were smart enough to weigh the car, that is the big bucks. Traditionally in the AD world, you are talking about 1 buck per mile. As you get more experience in DITY (Do It Yourself) moves, you become very cognizant of what to DITY and what to ship...weights for working out are the best, they take up very little room, but weigh a lot...clothes are the worst because they are so light. At the end of Bullet's career we would get a 3K+ check for our dity...of course we would get to the new base with the oddest things in the car...weights, grandfather clock weights, lamp bases, coolers used as luggage, same with the microwave, bed rails, etc. Anything heavy that took up the least amount of room. AND yes, if your car has removeable seats like a suburban it is within regs to ship them, so you can remove them and send with your household goods. The most important thing is to remember it will not be insured through the military, so only take things you know won't break.
So there is the tip of the day for future military members.