Takes around 3 and half to 4 hours, depending on part of city you are going to. But think they have introduced a new system for tolls - have to buy a card and scan it each time you go through. Office just before toll to buy the card from. If you go though the open lane and havent paid, you will hear a beep, which means you will be fined!
The road from Fethiye to Dalaman, onto to Mugla, then onto Izmir is being greatly improved so all journeys in the not too distant future will be reduced.