to get best perfroance and millage enine need certain temperature around 90c degree....making it direct fan never allow the temperature to each certain level
thus u get bad performance low millage on petrol..
plus in winters it will take alot of time to get engine Hot...which is not good
direct fans are only good..if you can control them from inside
like i have switch inside my car..i turn it off when starting in winters and normally..and will turn on as it gets to a good temperature