The Opel Vectra is not a Prius. You might see fuel consumption figures of 25-28 mpg (Imperial) in stop-start traffic. However, you can improve this significantly.
City traffic lights are often synchronized for 50 km/h (30 mph). The Vectra’s 5-speed manual gearbox is happiest at 2,000 rpm in 4th gear at this speed. If you accelerate hard to 60 km/h, you will hit every red light. Drive like a taxi driver—smooth and predictive. opel vectra city car driving
These factors make the Vectra frustrating as a pure city car. The Opel Vectra is not a Prius