Well it is ruined FOR SURE for a car. I hadn't thought of the A4 perhaps tolerating the low octane base stock.
Do note - and I learned this the hard way
- that the goopy ethanol/water mix does some combination of these two things if used as fuel:
1. Clogs up the filter/water separator and no fuel passes to the engine.
2. Gets through the filter and make a mess of the carb.
In both cases the engine is not going to run for long.