Connor Hedges, who is 19 and is studying biomedical science, was working as a delivery driver to help pay his way through university when the thief struck on White Lane in Gleadless.
The teenager, who will turn 20 this weekend, had just clipped a car and being the good citizen he is had knocked on the door of the house it was parked outside to inform the owner.
They were exchanging details when a thief jumped into his car and tried to drive off.
Connor leapt into action, throwing himself onto the bonnet in a desperate attempt to prevent him from getting away.
But the thief was undeterred and kept driving, throwing Connor off the bonnet before driving over his leg as he sped off.
Connor’s leg was badly broken in the horrific crime, which happened last Tuesday, January 27, at around 6.15pm, and he remains in incredible pain and is not expected to be out of his plaster cast for several months.
His plight shocked the community, which has rallied round to support him financially while he is laid up at home unable to work.
Hayley Mills got in touch with Jayne Mason, founder of the S12 Neighbourhood Watch group, to start a fundraising appeal, which quickly passed the £500 mark.
Connor’s mum, Sandra, said he remained in a bad way but had been touched by the response.
"He was swapping details with the woman when he turned round and saw the guy jump into his car,” she said.
“He jumped on the bonnet, thinking the thief would stop, but he didn’t. He flung Connor onto the road and drove over him, crushing his leg.
"He’s on morphine and codeine and his leg's going to be in plaster for about six months. He’s been getting by on adrenaline and too many drugs but I think it hit him yesterday how bad it was.
"From the bottom of our hearts we would like to thank everyone who’s helped. It’s taken a weight off his mind and means so much to us.”
Connor had been living at The Forge, just outside Sheffield city centre, but his mum is now looking after him at their family home in Elmsall, near Pontefract.
Sandra said it turned out Connor hadn’t even damaged the woman’s car that evening – he had just clipped the wing mirror, which he heard pinging back.
She told how he hadn’t got a good look at the thief, who is still being sought by police, because it was dark and everything happened so quickly.
And she revealed how Connor’s car, which had his phone, driving licence and bank cards inside when it was stolen, had since been found but was a write-off.
Jayne Mason, who helped set up the appeal, said: “What happened to Connor was awful and I’m glad we’ve been able to help a little bit. I’m not surprised by the response because I know we’re a really good community and when needed everyone pulls together.”
To donate to the fundraising appeal for Connor, visit gofundme.com/f/S12-nhw-appeal-for-Connor-lets-smash-this.