The motel, which opened in 1957, was the first one built in Victoria when it was constructed on the former site of the Mulgrave Arms Hotel.

According to Heritage Victoria, no architects were used to design the motel. The owner, Cyril Lewis, was believed to have influenced the design after travels to the US, where he stayed in and inspected many 1950s modernist motels.

Experts said the motel's distinct signage and electric lights were "closely tied to modern design in post-war architecture", with businesses at the time using the bold signs to advertise their services to passing motorists.

Conservation consultant Bryce Raworth, who was commissioned by Oakleigh Developers to prepare a report on the motel, said the site "quite clearly warrants the registration".

"It's an outstanding example of the early building type of the 1950s which is under-represented on the register and starting to disappear in Melbourne and Victoria more generally.

"It represents the emergence of a new building type associated with the economic and social changes occurring in Victoria after World War II. In particular, it reflects the dramatic rise in mass car culture.

"With its butterfly roofs, sloping window walls, sleek signage and hangar-like entrance, the building stands as a model of 1950s modernity."

Simon Reeves, of Built Heritage, who prepared a report on behalf of The National Trust, said the motel was of "considerable aesthetic significance as a rare, early and substantially intact example of the American Googie style of commercial architecture".

In a written submission, Oakleigh Historical Society president Felicity Smith supported its inclusion on the register because of its architectural significance and the need to preserve local heritage.