I remember back when it was called the Michelin MXV4 tire. My guess, is when they added the low rolling resistance they went with the Energy name.

The tire became popular for the hybrids. They added a S8 designation to the Energy name in 2006/07. I have no idea what thats for, maybe some slight improvement. I read months ago that Michelin may be coming up with a newer MXV4 Energy with improved traction.

My '07 TCH came with the Energy S8 tires. I keep 40 psi cold in them and they are wearing evenly nearing 10,000 miles.

I really like the smooth and rather quiet ride of the TCH.