I have several studies that show running E30 improves mileage when compared to E10!

2005 AWD Escape Hybrid
Best tank trip MPG 39.02 (scangauge II) for 402 miles on I-70, 10.3 gallons used over mostly flat terrain.

Best tank trip MPG 34.6 for E30 for 271 miles along I-80 in Indiana and Ohio.