Just an update, really:
The speedometer was set to kilometers rather than mph. Never was a problem. Hadn't realized that it could be changed, but I figured it out. Had it put on a computer and driven by mechanic just in case. It's perfectly fine.
Had the "bump" fixed. There was a loose rod that would hit the bolt whenever the car was put into gear. Bolt was tightened, all better.
Thanks to all who read my question and maybe tried to come up with an idea or two.
Tuesday, June 12th, 2007 AT 8:03 PM