✔ 最佳答案
there is a bus route which runs thru the romantic road. pls see the below web site:
http://ourworld.compuserve.com/homepages/euraide/roman002.htm
http://www.ricksteves.com/blog/index.cfm?fuseaction=entry&entryID=157
Normally you can start at Frankfurt and end at Munich, or vice versa.
However, Heidelburg is out of the way and you need to take train separately. Although it is not far away from Frankfurt but as you only have three days, you may not have enough time to visit all sites in the romantic road.