At the Tenerife and other Canarias islands established special economic zone, so fuel are cheaper than at the Spain.
Standard 95 gasoline petrol fuel costs usually around 1.00 per liter. Biggest chains of stations is BP and Disa.
Diesel (gasoil) costs 1.10 EUR per liter. LPG price is around 0.55 EUR.
At the some gas fuel stations price a bit lower, for 1 liter 95 is around 0.90 EUR (Repsol, Cepsa, GM)
Small gas station Tu Trebol in Adeje sells fuel with discount 1%, price is 0.95 EUR.
Also you can have a discount 1% at BP, if you have a discount card Hyperdino.