Yes it's a joke, read there about us page. Here's a quote;
Just in case you are an American, or possibly drive a car made by Suzuki (except for the new snazzy new Swift), we will spell the purpose of Petrol Direct out to you in simple terms. This is a spoof. A parody. We do not sell petrol or any other fuels, and certainly not plutonium or antimatter. Sorry. This site is strictly for laughs only.