[sallen]

Just my $0.02

I've run 8 (2 sets) of Energy Savers over 8000 miles and agree there was no 3-4% increase in MPG (even when corrected for size as they were narrower but a taller aspect than the tyres they replaced).

In my application tyre noise was much worse, and dry grip terrrible - even compared with the ditch-finders I had on before. That said, the ES's were 20mm narrower and the loss of grip was more progressive than the wider no-brand tyres.

I also must say they are very durable (the tread anyway). Of the 8 tyres I ran they died in the following ways:

5x deep cracking with significant tread left (they seem to crack with age rather than wear down);
1x popped a cord and went egg-shaped (much vibration happened);
2x survived and were on the car when I sold it.

They also have the benefit of being OEM equipment on lots of cars in Europe, so are cheap to find - usually on steel wheels when the owner has changed to some aftermarket alloys.