However, diesel models are usually more expensive to buy than equivalently-powered petrol versions, and unless you do a high annual mileage, they won't work out cheaper to run in the long term. This is particularly true for small city cars - most will have very economical petrol engines anyway.
Check out the tax bandings, though, especially if you'll need to drive into central London (low-emissions cars in Bands A and B will be exempt from the congestion charge as of October 2008).
Or something greener?
There has been much publicity and hype around hybrid petrol-electric vehicles such as the
Toyota Prius. Most of these do offer substantial advances in overall fuel economy - though not necessarily any greater improvements than opting for a diesel engine.
The hybrids do have significant advantages around town, where some (including the Prius) have the ability to run on zero-emissions electric power only, but fuel consumption can be heavy at higher speeds. They can make sense if most of your driving is urban, but otherwise, you'd be best off with a diesel (diesel-electric hybrids, offering the best of both worlds, are still some way off production). A diesel fitted with a
particulate filter, of course.
For city commuting, an electric vehicle is viable if you have access to a recharging facility. Some city supermarkets now have recharging points in their car parks, some local councils have installed them on-street and a few new-build housing developments are also putting them in.
However, most EVs currently on the market still have a very limited range between recharges, and cannot go faster than city speeds; some are also very limited in their versatility, and are very lightweight and flimsy, offering little more protection than a motor-scooter in the event of a crash.
LPG (liquid petroleum gas) conversions are falling out of favour, as these offer limited environmental benefits and incentives such as exemption from the London congestion charge are being phased out.
Don't expect the tax-break on LPG fuel to last much longer, either, and many petrol retailers are now replacing their LPG pumps with pumps dispensing
E85 (bioethanol). Bioethanol models - such as the Biopower Saabs - are a better long-term investment, and if you can't find an E85 pump, they'll run on conventional petrol.
Volvo offers CNG (
compressed natural gas)-compatible vehicles, but this fuel has never really taken off in the UK - shame, as it is clean-burning. You can even refuel from a domestic gas supply, though most people using CNG in the UK work around a central depot with fuelling facility.
