[Prodigal Son]

I can't believe they'd throw people in jail for 7 years or even impound their car for that matter. What exactly would the charge be? We don't have a diesel but I'll definitely think about buying one and doing this.

[UKCajun]

The charge: TAX EVASION.

The "culprits" are evading the UK fuel tax by using either recycled fish and chip shop cooking oil, or cooking oil that they buy at ASDA supermarkets and the like. However, even though the pay VAT (value added tax) of about 20% on the cooking oil they buy at the supermarket, that doesn't count. They need to pay fuel tax too.