Here's my crazy scenario driving home from work tonight: I was driving for about 5 miles at 65 mph when suddenly the gauge shot straight up almost to the red zone! I slowed down, got in the right lane to take an exit, cursing and praying (!), then-it returned to normal! I drove 20 more miles, pulled off the interstate and relaxed (2 miles from home), then it did it again! I stopped, felt the hood, smelled around and no apparent problem. When I started it up again, gauge returned to normal. I just checked my coolant after she sat in the garage for 3 hours. It's normal level.