Many of London's high-emissions sports cars and luxury limousines are being registered as minicabs to avoid encurring the congestion charge, it has emerged.A number of sports cars, including two seaters like the Mercedes SL, have been fraudulently registered for private hire, according to data published by website www.cleangreencars.co.uk. Minicabs are exempt from the £8 per day central London congestion charge – which is set to rise to £25 for high-emissions vehicles next year – and anyone can register their car as a taxi for a one-off £82, followed by a £27-per-year licence fee, according to the 'site.Other cars on Transport for London’s list of legal minicabs include two Maserati Quattroportes, eight Rolls-Royce Phantoms and one Aston Martin DB7. This practice is not strictly illegal – there’s no stipulation that owners have to hold a minicab licence to register their vehicle and it’s almost impossible to regulate whether they ever carry paying passengers.The Private Hire Vehicles (London) Act 1998 does say that taxis must be deemed ‘suitable in type, size and design for use as a private hire vehicle’. However, this legislation is geared towards ensuring the roadworthiness of vehicles, and doesn’t specify that they require rear seats. Transport for London is investigating the situation, now that it seems their private hire licencing system is being swindled. And while coming home from the pub in a posh Mercedes SL, rather than a ropey Vauxhall Omega taxi, sounds fine to us, we don’t expect to see one in a Soho taxi rank next Saturday night.