I have switched to using gasoline with alcohol added in my car. This gasoline has a higher octane rating and is supposed to work better in older cars. A neighbour uses it in his car and it made his run better, but my 1978 Chrysler seems to run worse. Gasoline with alcohol added does have a higher octane rating. The cooling effect of the alcohol evaporating keeps the fuel from self igniting.
Ethanol alcohol is the most common type of alcohol used.
It has a cleaning effect on fuel tanks and may cause the fuel filter to plug up initially until the tank is clean. Methanol has also been used with gasoline, but it is highly corrosive so most auto manufacturers do not recommend it. The gas retailer can tell you what type of alcohol is mixed with the gasoline. The alcohol is also an oxidant. It chemically breaks down in the engine's combustion chamber to produce extra oxygen.