Yes it is, although diesel-engined cars are generally more suited to longer journeys than they are to stop-start town traffic. You'll find that a modern small capacity (1.5-litre or less) turbo petrol engine will be very nearly as efficient as a similarly powered diesel at lower speeds. Petrol is cheaper at the pumps too, which is worth thinking about when considering which fuel type is best for you. Modern diesels are much cleaner than they were in terms of emissions, but many ranges are now petrol-only; the Ford Fiesta andVolkswagen Polo, for instance, which once used to have solid diesel choices, no longer provide any diesel models.