Palliser F5000
You've got the right car. It went by three different names, though. At the time of the puzzle photo it was called the "Franklen 5000" after its creators, Frank Gardner and Len Bailey. They sold it to Palliser and it became the "Palliser 5000." Palliser then sold the car to Alex Mildren and it was re-dubbed the "Mildren 5000."