Yes, even small amounts of alcohol affect you. The more you drink, the more intoxicated you become. You may not sense an increase in intoxication, but how you feel does not matter – if you have consumed alcohol you are affected by it and therefore should not drive. It is as simple as that.
Driving with less than 0.1 per mille blood alcohol is not only dangerous, it may also be illegal. The limit for drunk driving is 0.2 per mille blood alcohol. However, a driver with less than 0.2 per mille blood alcohol may be found guilty of drunk driving if he or she has not been able to drive in a safe manner.