Watling, 28, was found wearing only a T-shirt and bra after Parbat crashed on the A2011 in Crawley, West Sussex, on 9 March last year. The rest of her clothes were found in the car’s footwell.
At Lewes crown court, Parbat told his trial that Watling, a hair salon worker and mother of two, had said she felt “horny” and invited him to pull down his trousers as he drove along.
Parbat showed no emotion as he was also banned from driving for three and a half years following his release from jail and ordered to pay a £120 victim surcharge.
Griffiths told him: “I’m satisfied that the cause of the accident in which Lisa died was your decision to continue to drive your motor vehicle at a speed approaching but not exceeding 70mph while engaged in some form of sexual activity with your trousers partially down. I make it clear that the blame for this tragic accident is entirely yours.”
A motorist who took part in a sex act with his girlfriend moments before he crashed has been jailed for seven years for causing her death by dangerous driving.