A magic tablet that will cut harmful emissions from your car by two-thirds? It sounds too good to be true. SARAH LEWIS finds out that, sadly, it probably is...

Sales rep Phil Forgham of local company Save on Petrol is prepared for scepticism: "As you and I both know, when you introduce something to the UK market which is this beneficial, people are very sceptical and generally dismiss it."

A truism proved neatly by my inclination not to believe a word of it when he claimed to be able to cut greenhouse gas emissions from a car by a whopping 75 per cent, as well as increase fuel efficiency by up to 14 per cent, using a simple tablet with a secret formula called MPG-CAPS.

I wondered why, if there was something which really could cut harmful emissions by two thirds, had such a glorious invention not been all over the news, you know, like when people realised using unleaded petrol was a good idea?

"Well," Forgham said, "a lot of the petroleum companies don't want people to know about this because they are getting £1 a litre. The American army has been using it for 27 years and now, with oil prices and climate change, it has been released to the general public."

Right.

He suggested I test the supplement, saying he had someone who would measure the emissions before and after trying the tablets.

So the hunt for someone to volunteer their car began.

Meanwhile, I received an email, signed by Forgham but not from Save on Petrol, from a company called Fast Track Fuels.

"This just might be the single most significant environmental story you have ever seen, Sarah," it read.

How exciting!

A request for peer-reviewed scientific studies led to the "media room" of a company called Fuel Freedom International (FFI), which is, apparently, "the media's best source for stories, insight, and information on fuel efficiency, reduced emissions and lower fuel costs".

Conveniently, it is also the supplier of Save on Petrol's MPG-CAPS.

A few days later, some bumf landed on my desk, propping up Forgham's claims of amazing savings, both financially and environmentally. MPGCAPS are even US Environment Protection Agency (EPA) registered, number 201220001.

But a little research shows all the EPA number means is it will not harm your car or the environment. It does not necessarily mean it will work.

Not being an expert on internal combustion engines, I called the RAC.

"They use a lot of big words but there are no recognised findings or test results," a spokesperson said. "We are not familiar with this particular product but over the years we have been approached by many companies who claim the same thing. We are not in a position to say it does or does not work but a lot of them don't."

The AA only had similar things to say: "We've seen many hundreds of these fuel-improving items over the years and our general feeling is, until the manufacturers provide scientifically verifiable evidence they work, it is very difficult to encourage people to use them. The simple fact is, if they were as good as they claim, they would be standard issue.

"As for being environmentally friendly, some simple tweaking of your driving technique can save you petrol and boot-loads of carbon dioxide without costing a penny." (See panel) And again, the Motor Industry Research Association (MIRA): "We turn down very little work here but we deliberately have a policy to not test any of these fuel supplements because they invariably want to leverage our brand to make theirs more credible.

"Look at it this way, do you really think the petrochemical industry is going to be outdone?

"We are not saying they definitely don't work but it will either be a lubricant, in which case you are better off adjusting the actual oil, or it will be an octane booster, which will do nothing unless you alter the engine map. "

I was still waiting for the rush of people keen to save their 75 per cent to get in touch when I decided to have a look on Google.

The first thing to notice is MPG-CAPS do not seem very popular in America.

FFI is being investigated by the office of the Attorney-General of Florida for "unfair/deceptive business practices in the sale of a product that purports to make gasoline burn with greater efficiency without independent scientific testing to substantiate the claim".

Back in 2004, the Federal Trade Commission, an independent consumer protection agency of the US government, was seeking to shut down a similar company with claims almost identical to FFI.

There are hundreds of pages discrediting both the company and the product.

One site, www.carbibles.com, run by a self-confessed "petrol-head", had already performed the test Forgham was so keen for The Argus to run.

Using a 1995 Volvo 850 Turbo, the site owner tested the tablets between home and work. He found, on average, fuel efficiency actually dropped by about 2mpg.

FFI responded saying the tests were unfair because of the age of the car.

However, one of the claims on their website is "MPG-CAP will improve the performance of older cars".

And that is just one of many inconsistencies. The petrochemical industry conspiracy theory, for example, does not really add up.

Cars are being subjected to ever more strict emissions regulations and technology is working hard to keep up.

If a 75 per cent cut in greenhouse gases really was possible with a simple tablet it would, as the AA commented, surely be standard across all fleets.

Most importantly perhaps, the magical 75 per cent emissions saving is never explained.

Still, Phil Forgham will not be swayed. "How do they know it doesn't work?" he says of the AA, RAC and MIRA. "What tests have they conducted?"

I phone the 60-second recorded information hotline promoted by the sales bumf.

"The global market is OPEN!" it tells me. "Are you a self-starter looking to earn a six or even seven-figure salary?

In the first 90 days we sold in excess of $2 million in products, making it one of the most successful launches in US history. In the first 12 months we made over $60 million in sales."

I ask Phil again why no one has heard of it.

"A lot of people ask me that - and I say simply because of our route to market. We use word of mouth. We don't have thousands of pounds to invest in advertising."

Deadline rolls around and still no one has volunteered their car for the MPG-CAPS trial.

Changes that really do work

The AA recommends some fuel-saving tips that won't cost you a penny:

  • Slow down. Dropping from 85mph to the legal limit of 70mph saves 0.4 litres of petrol every ten miles - or 30p to 40p.
  • Go easy on the air-con. Air-con adds about ten to 15p every ten miles. Use the air vents, where possible, to cut fuel consumption and cost.
  • Mind the traffic. Small cars stuck in traffic jams use up to a litre of petrol every hour, that's 1.5p a minute. Medium and large cars can double that. Avoid rush hour and always check the traffic report before you go.
  • Remember the small things. Under-inflated tyres, an empty roof rack and open windows can each add 2.5 per cent to fuel consumption. Excess baggage in the boot also adds to the cost of fuel.