Childrens story book about a Jeep?

Gi'day Group.
When I was a kid in primary school, I remember reading
a series of books about Jeeps.
The story is about a young Boy who stays at the grandparents farm
and when exploring he came across an abandoned barn/farm.
Inside the barn was an old Jeep which he got running and
drove around. The next book dealt with owner showing up
and he then tried to buy it.
Anyone know of this story. I like to find out so as to get
a copy for my nephew. Almost considering calling the
librarian at the school. But Jeepers I haven't been
in that school in almost a century :-)