hi there,
Unlead petrol about 15 baht/litre (= about 25 pence/litre)
If you want a car then check out Via Car rentals web page http://www.phuket.com/carrent/via.htm
You can rent a Suzuki jeep or similar from the roadside independants along the beach from about 800 Baht. We rent our jeeps to about 700 baht/day and small motor bikes from 120 baht/day.
See our web page http://phuket.ksc.co.th/~orcella
Have a good holiday,
Wallee & Alex in Patong, Phuket