Originally Posted by Gourmet Greg
Also, I think it's quite possible that both the roast and the vegetables may give up some moisture which will join the Coke "broth" and there might be even more liquid after cooking is finished than at the start. (This is supposition. It would be interesting if somebody knows if this is likely.)
Yes, you'll end up with more liquid than you started with. Little moisture is lost to evaporation and, as you said, the ingredients (especially the meat) will give off liquid. When adopting conventional recipes to a slow cooker, it's usually suggested to reduce the added liquid by about one cup. Also, veggies in general take longer to cook in a slow cooker than otherwise. That's why most slow cooker recipes call for chopping the veggies into smaller pieces and adding them to the bottom of the crock (where the increased heat will cook them faster).