OK! I FINALLY got around to doing this...
Within the past year or so, I happened to score both a set of nearly new
Dunlop Enasaves on alloys AND a set of nearly new
Bridgestone Potenza RE92's on steelies.
Both are 165/65R14 size, and are the OEM tires on the 2014-2024 (?) Mitsubishi Mirage and the 2000-2006 Honda Insight.
Coinkydink: I have owned a 2000 Insight and have owned a series of Mirages...
(Current car: 2014 Mirage 1.2L, 5-speed Canadian base model with no A/C. Curb weight under 2000 lbs! Thread: 3rd time lucky! Bought yet ANOTHER cheap, 3-cyl Mirage eco-appliance)
[ Thread: MetroMPG's Honda Insight boat tail extension (cardboard) tuft video; ABA test +9.7%... and ... Thread: Got a new UFO*: 2000 Honda Insight 5-speed (ailing IMA hybrid battery pack) ]
The RE92 is widely regarded in the Insight community as the best tire for MPG. (The Insight has very low aerodynamic drag, so reducing rolling resistance is a key consideration because it makes up a higher proportion of total drag than the average car. It helps the car enter & maintain lean burn at higher speeds.)
Long story short: in my simple coastdown test, both tires rolled almost identical distances.
Testing details:
-- Ambient temperature: 24 C / 75 F
-- Tire pressure: 55 PSI / 3.8 bar
-- Tread depth: Enasave = 5.6 mm / 0.22", RE92 = 5.1 mm / 0.20"
-- Tire + wheel weight same for both sets (both tires are 13 lb + 14 lb wheels)
-- Each set of tires got 4 coastdown runs, plus one last run after switching back to the first set.
-- All runs done back-to-back (same day, same conditions)
-- The testing area is 2 blocks from where the car was parked overnight, so tire temperature should have been extremely close for both sets (but not measured).
-- The car was positioned at the same point on a slight hill, then allowed to roll out to a level section, where the distance was marked on the pavement.
-- To minimize the potential of brake drag affecting the results, the car was stopped/positioned using only the handbrake rather than the hydraulic (foot) brakes.
Results:
-- The average coastdown distance was around 34.7 m / 112 ft.
-- The end points for all 9 runs were clustered within the last 122 cm / 48 inches!
--
34.6 m / 113.6 ft ... Ensave average coastdown distance
--
34.7 m / 113.7 ft ... RE92 average coastdown distance
Conclusion
How much faith would you put in this test? Enough to say that both tires appear to have similar rolling resistance? It sure seems that way to me.
If it's a valid & accurate test, then Insight owners should be happy to know the Enasave appears to be a viable alternative to the RE92 in terms of preserving MPG performance. (There are always fears in the Insight community that the RE92 is going to be discontinued. Although it was still available as of a year or 2 ago as far as I know.)
I'm not sure which tire costs more, but that would be a consideration for many people as well.