How fast does a 1998 Honda have to be going to roll a 2014 Chrysler Town and country van and slide 10 to 15 ft on the side
20 MPH should do it. You have to consider road slope amount of incline or decline, speed of both vehicles or lack of speed of one. Once the point of no return is reached, it doesn't take much from there on, so if there was any more speed added it would amplify the accident.
A 3,000lb Honda traveling at 45mph would create an impact force of AT LEAST 11 tons. A 14 Town and Country only weighs 4600 pounds. So I would say it was doing the speed limit or under.