A couple of things I noticed about supply wagons. These are from playing the Jena 06 scenario.
I had several French corps in Berlin. It was near the end of the scenario, and I wanted to go up and take Stettin. So I sent two corps. First I moved Davout's. This was mainly infantry and artillery with a power of 500+. This move came up as a 12 day move if I remember correctly. Then I moved Murat's corp, which was I think all cav with horse artillery. It took three days.
I'd be ok with that except for one thing. Since it was winter at the end of the Jena scenario, I had supply wagons with both corps to try to absorb weather hits. So, even though Murat was mostly cav, I'd have expected him to be slowed down to almost the same speed as Davout as both were tied down by supply wagons in their columns.
Having Murat move so fast makes me wonder if the supply trains are slowing down the columns correctly?
Are there any other units that would be slower than a supply wagon? That's only other reason I could think why Davout would be so much slower. Even then, 3 days for Murat to go from Berlin to Stettin with supply wagons seems awfully fast.
The other thing I noticed is that I was moving a column of four supply wagons across my back areas. They were moving from Frankfurt up to Kessel where several corps were regrouping just as winter was starting to hit. When bad weather attrition was starting to hit, this column got clobbered. The sub-elements were down to about 1/3rd strength. The funny thing was they were still almost full of supplies.
I thought the presence of a supply wagon was supposed to absorb hits by burning supply instead of taking the hit? Is this not true when supply wagons travel alone? Because this column took almost all hits to the units while the supplies were at a level of like 18/20 in the elements.