Supporters of the LPG industry described the occasion, held at the Shell autogas station in Victoria, London, as a milestone event.
Wilson said: 'The 100,000th LPG vehicle is a significant landmark in the take-up of LPG vehicles in the UK. The industry has responded well to the Government's support for LPG.
'The consultation on the future of Government support for road fuel taxes gives all of us a chance to secure the environmental and social benefits of LPG. I am particularly anxious to promote it in rural areas where the savings to motorists can be greatest.'
The vehicle's new owner, OCS, which already has 52 LPG vehicles on order, runs a fleet of 2,650 commercial and privately-run vehicles, of which 400 travel in and around London.
Bosses at the company say they had previously been deterred from ordering LPG vehicles in the past because of the initial purchasing costs and lack of availability of the fuel.
Two factors which have contributed to its decision to invest in the fuel is the exemption of LPG vehicles from the £5 per day London congestion charging scheme and its environmental credentials.
OCS head of procurement Tim Murray said: 'The economics of introducing more LPG vehicles into our fleet means we can maintain our competitiveness in the facilities management sector. Also, for the increasing number of customers who ask for it, we shall now be able to provide a measure of our environmental commitment.'
Driving the Vectra Dualfuel will be OCS London regional manager Mark Pollard. He said: 'I have always been interested in environmental issues and am delighted my company car will be LPG-powered and helping the environment. The 100% discount on congestion charging is a bonus.'
The car is leased by OCS from Lloyds TSB autolease whose green fleet development manager Malcolm Noyle, also spokesman for the Clean Fleet Alliance, said: 'We cannot underestimate the importance of this milestone.
'With 100,000 vehicles on the road, as well as more than 1,250 refuelling sites, the barriers to achieving greener, more cost-effective fleets are tumbling. We are delighted our client OCS has grabbed the opportunity to save money and boost environmental performance by including LPG vehicles as part of their UK fleet.'
And speaking at the event, Howard Kerr, chairman of the LP Gas Association, said: 'The event is a great tribute to the 100,000 UK motorists who have, between them, invested about £200 million to convert their vehicles to run on this clean fuel. It is also testament to Government policies that encourage the uptake of cleaner fuels through duty and grant concessions.'