Magnus Hollis and his girlfriend Catherine Allfrey have been left devastated by the theft.
Mr Hollis, 25, spotted the thieves from his bedroom window on Brighton seafront and shouted out: "Get off - that's my car."
One thief shouted back "tough" as they pulled away.
The gleaming 1967 F-reg' Minor, transformed from a rust heap, was then taken for a joyride before being set ablaze and destroyed in Buckingham Road, Brighton.
Mr Hollis was in tears as he said: "When you've been living and breathing a project like this for so long, and then see it destroyed just for some perverted fun, you just cannot begin to describe how you feel."
His girlfriend Catherine, 32, helped with the restoration.
She said: "It was like a baby, a member of the family. The car was in a dreadful state but looked wonderful - and we'd just finished it last weekend."
Mr Hollis, who bought the car for £200 and reckons it was worth £2,000 when restored, is now offering a reward.
He said: "I made and repaired panels, repaired the mechanics, brought the colour back to its original almond green, matched up floor carpets and Catherine made up the cloth material for under the roof.
"I did the work in Catherine's mum's garage and she made me endless cups of tea and meals while I worked in there.
"I just hope the thieves read this so they know how much love and patience went into it."
Anyone who witnessed the theft in Kings Road between midnight and 1am on Easter Monday, or who saw the car being dumped later, should contact the Brighton police crime management centre on 001273 606744.
Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.
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