Monday I took delivery of a Toyota RAV4 4x4 hybrid. 2.5 petrol and self charging electric. Towed my  heavy caravan with it today and was really quite surprised. I thought it would be entirely petrol but not so. On the flat and downhill it switches to electricity. Cruise control it switches to electric once a steady speed is achieved, only changing to petrol to accelerate or hill climb. I've only done 102 miles but it's achieved 30.1 mpg average. Manufactures figures I think said 50.4 m