Q: For many years I've been wondering why so many vehicles have an RPM dial when no one uses it. What purpose does it have, and who benefits from using it? It takes up a lot of space on the dashboard.

Q: My Ford had a dead battery. When I jumped it, the speedometer stuck at 160 miles per hour and the tachometer is stuck at 6,000 RPMs. What can I do? Car Doctor: How to spot a 'flood' car before you ...