Prince Charles reviewed a selection of the vehicles taking part in the rally and then drove the Ford Focus FCV up the main driveway to park in front of Hampton Court Palace.

This event was the official flag raiser for the rally, which followed in reverse the route of the London to Brighton Veteran Car Run. The objective of the rally was to bring tomorrow's alternative fuel technologies to the capital.

Participants in the rally assembled in Madeira Drive in Brighton on June 5 with Ford represented by future and current models that are leading the auto industry towards reduced carbon emissions.

Two hydrogen-powered Fuel Cell Vehicles (FCV) were the centrepiece of the blue oval's line up: the Ford Focus FCV and a Ford Explorer FCV, which had its European debut on the event. Accompanying the advanced-technology FCV models were Ford Focus Flexifuel cars, representing low-carbon models that are on sale now.

Coming to the UK from Ford's Advanced Vehicle Research Centre in Aachen, Germany, the Ford FCV models were both driven on the rally by motoring journalist and event supporter Quentin Willson.

The Aachen Research Centre is currently running the vehicle as part of its participation in Germany's fuel cell vehicle test programme, which includes real-world testing in Berlin where a pilot hydrogen refuelling infrastructure operates.

At the rally finish in Trafalgar Square, Quentin Willson joined on stage Nicky Gavron, Deputy Mayor for London, who congratulated rally participants and welcomed the principles behind the rally.

Roelant de Waard, Ford of Britain chairman, said: "Ford and rally organisers Revolve are closely aligned in promoting sustainable transport solutions such as FCVs, hydrogen, biofuels and other options. This rally deepens the understanding of greener motoring – not least among the welcoming party of politicians at Trafalgar Square."

FCVs run on electricity generated from a fuel cell stack. In the stack oxygen and hydrogen are combined to produce electricity, with water vapour as the harmless by-product. The electricity is used to power a motor/transaxle, which drives the wheels.

While Ford has made strides in hydrogen storage capacity – a crucial area for a fuel cell to achieve a travel range comparable to today's cars – other challenges remain before FCVs become commercially viable .

Low-carbon technology represented in the eco rally which is affordable now is the Ford Flexifuel range. Ford Focus and C-MAX Flexifuel bioethanol/petrol cars cost the same as equivalent petrol-only models. The Ford Focus was the first Flexifuel car on sale in Britain and in early 2008 Flexifuel versions of the new Ford Mondeo plus S-MAX and Galaxy models will be added.

Existing clean diesel engines are also increasingly recognised for their low CO 2 credentials. The Government's 2007 budget set vehicle excise duty at £35 a year for at least three years for cars emitting less than 120g CO 2/km – boosting further the appeal of the 17 Ford models falling into this bracket. They include Ford Fiesta 1.6 TDCi at 116g CO 2/km and the same engine in the Ford Fusion Multi-Activity Vehicle producing 119g.