Mrs Whitcombe, 73, was stunned when she received a call from Arndale Centre Manager Bill Plumridge on Christmas Eve to say she had won the Vauxhall Agila.
She was among thousands of people who entered the draw, helping to raise a massive £19,000 for more than 30 charities. In total, the Arndale Centre has raised more than £150,000 since its first Win A Car draw in 2000.
Mother-of-three Mrs Whitcombe, of Baldwin Avenue, Eastbourne, said, "When Mr Plumridge called to say I had won, I honestly thought he was joking. My grandchildren couldn't believe it either and were jumping for joy. Even our friends in Sri Lanka were over the moon. Everyone has been so pleased for us.
"I've won the odd raffle prize before, but nothing like this. It really is the most wonderful Christmas present. I intend to use the car as I drive most days. It's a lovely car.
"I only entered the draw to help the charities taking part, and never expected to win. I was just pleased to do my bit to support so many good causes."
Mrs Whitcombe will soon be driving away her 1.2i 16v Club five door Agila, brimming with luxuries including air conditioning and an MP3 player, supplied by Eastbourne Motoring Centre.
Each year, charities who take part in the draw are given a day to sell tickets and receive all the proceeds from their day's ticket sales.
Mr Plumridge said: "We are delighted to present this year's car to our lucky winner Mrs Whitcombe, but all the charities that took part in the draw are also winners. We are thrilled they have raised so much money.
"The draw continues to go from strength to strength and we hope to run it again next year."