1. Calculate the fuel consumption for the trip:
Fuel consumption = Distance / Fuel efficiency
Fuel consumption = 3.7 miles / 35 mpg
Fuel consumption ≈ 0.106 gallons
2. Determine the cost of petrol based on its price:
Cost of petrol = Fuel consumption × Petrol price
Cost of petrol = 0.106 gallons × £6 per gallon
Cost of petrol ≈ £0.64
Therefore, the petrol cost for a 3.7-mile trip with a 35 mpg vehicle and petrol at £6 per gallon is approximately £0.64.
Please note that this calculation provides an estimate and can vary based on actual fuel efficiency, traffic conditions, and petrol prices.