We used Auriga Crown last time. £27 for 3 days but we did have to queue for quite a while to get the car. Generally for 3 days or less they all do full to full with fuel but check first. The best service I've had is from carmalaga They are based just outside the airport but bring the car to you. It took less than five minutes from leaving the arrivals hall to getting in the car. You drop the car off at their depot and they take you to the airport, it's less than a 2 minute ride. Best of all they do full to full fuel regardless of the hire time.
Taking the toll roads the journey is a little less than an hour, about 60 miles door to door. I think the tolls add up to about 8 euros each way. It's an easy journey and once out of the airport you only need to change roads about 3 times, getting onto the toll road, getting off the toll road and getting onto the coast road. The exit for Arenal is directly off the coast road so no searching involved. We take the E-15 from Malaga all the way to Estepona (3rd signed estepona exit) then the coast road to Duquesa. The exit for Arenal is about 50mtrs before the Duquesa exit.
Kevin