The legendary driver, who was killed in a helicopter crash near his home in Lanark in 2007, and it had taken him to five stage wins in the World Rally Championship a decade earlier.
Other cars sold for the lifeboat charity at Duxford, Cambridgeshire, include a 1960 Ferrari 250 GT with a Berlinetta chassis 1995 GT. It was one of only 167 ever made, and 10 supplied to the UK.
There was also a Jaguar E-type once owned by the footballer George Best and bought for £43,000.
A racing green 1976 Jaguar XJ-C 12 driven by actor Patrick Macnee when he played John Steed in The New Avengers TV series, sold for £62,000, well above the guide price of £10-12,000.
They were left as a legacy to the charity by businessman Richard Colton, who requested money raised from their sale be used to build a new lifeboat called Richard and Caroline Colton, named after himself and his late wife.
The lots have been described as the most generous gift ever left to the charity.
Simon Hope, chairman of H&H Classics which is ran the event at the Imperial War Museum said: "We are honoured to have been chosen to handle this sale which is of national significance.
"These stunning motor cars have been with Richard Colton for 40 years and meant a very great deal to him. So we are absolutely committed to realising the maximum amount for the cars."
Mr Colton, who died earlier this year aged 82, was a Northamptonshire-based businessman who made his fortune in footwear distribution.
He collected the classic cars throughout his life and was described as being "nervous" at sea.
Guy Rose, legacy manager at the RNLI, said: "We are deeply grateful and humbled by Mr Colton's generous gift and his decision to benefit the RNLI in this way.
"Six out of every 10 lifeboat launches are only made possible because of gifts left to us in wills, so they are vital to saving lives at sea.
"Mr Colton's generosity will be felt most by our volunteer crews and the people whose lives they save."