Call to stop inexperienced motorists driving sports cars.
The Institute of Advanced Motorists said the case of Satvinder Singh Nijjer, who was found guilty of causing the deaths of Miss Lavinia Carrington, aged 78, and her 76-year-old sister, Winifred, by dangerous driving, highlighted problems with existing controls for young motorists.
Nijjer, who has yet to be sentenced, lost control of his pounds 14,000 944 Cabriolet at 70mph while trying to impress his friends in February last year.
At the end of the trial at Stafford Crown Court, Judge John Warner launched a scathing attack on the teenager's father, Mr Surrinder Singh Nijjer, for buying his son such a high-powered vehicle for his 18th birthday.
As he called for a pre-sentence report, the judge told the court: "I don't suppose it will appertain to the fact of what on Earth his father was doing in providing him with a car way beyond his capabilities."
Mr Christopher Bullock, chief executive of the IAM, said it was socially irresponsible to allow any untrained person to drive a high-performance car.
"New drivers are enough of a risk to themselves and others without the extra challenge of a powerful car," he said
"Everyone who has an influence - parents, car manufacturers and dealers, insurance companies and legislators - should play their part."
He called for the law to be tightened to block inexperienced drivers from driving sports cars immediately after the basic L-test and called on insurance companies to think twice about giving cover unless the applicant could prove he had undertaken addi tional driver training.
After Nijjer's trial, Mr James Pillar, Porsche PR manager, said it offered all customers driving courses.
"Regardless of age or background, we offer all our new and used customers advanced driving courses which have a very high take up."