continuous extra consumption according to E85 test Omega A 2,6i

The following problem: I recently had a test with about 50% E85. my Omi (Omi A 2,6i Caravan) ran without any problems. However, there was an additional consumption of about 1.5-2l /100. I was able to refuel E85 for 0.96 EUR. Unfortunately, the tank is not exactly around the corner, so I left it at the try. Now I have already refuelled 5-6 times, only the consumption is still as high as with E85 Mix. My driving pr ofil: about 40% city 30% Bab 30% landstr. consumption before test: 10-12litres after test up to 14 liters (display BC but also measured) Has someone an idea mfg MM