I've always been interested, started doing this seriously in 2004 - due to having a girlfriend living 400 miles away
Which was quite a good reason to save fuel with UK prices being what they are.
Extreme hypermiling since I joined (I had experimented with engine-off coasting before but decided it was not worth it. Because I had driven a work car with a diesel engine and an MPG gauge (Avensis D4-D), and saw how efficient the idle was. After joining the site I realised the error of my ways (because my car is petrol).
Before joining I once got 90MPG(UK) on a 100 mile journey with no elevation change in the D4-D, which is about double the official figures, and I only drove slightly slower than most people would. This is when I realised the importance of instantaneous feedback!