Their mother Claire Raddie said she got an excited call from her eldest daughter who was working in a chemist nearby, but did not initially believe the news.
Convinced, she then took her youngest daughter down to the car park where LeBlanc was happy to pose for pictures.
Raddie, aged 39, of Cannock, thanked the star on Twitter, saying: "Sorry for the breakdown but you've made my two daughters very happy in Cannock!"
She added: "Totally unexpected but thank you so much."
The 48-year-old ex-Friends star was revealed among the programme's new line-up of hosts earlier this month.The Top Gear duo kicked off filming for the first episode of the new series with a 370 kilometre road trip to Blackpool, setting off from BBC's Broadcasting House in London on Saturday.
Also joining the line-up are Formula 1 commentator Eddie Jordan, German racing driver Sabine Schmitz, motoring journalist Chris Harris and car reviewer Rory Reid.
LeBlanc tweeted ahead of filming, calling the Top Gear crew a "great group of lunatics" and adding: "We start filming in the morning. I'm pumped."
- PAA