Cars and watches have always enjoyed a close relationship, with wristwatches gaining popularity at roughly the same time as motor vehicles, in the early 20th century.

These days, the relationship between the two industries is big business, allowing companies to reach more buyers thanks to cross-branded collaborations.

While this list could have easily been three times longer than it is, here is our Top 10 collaborations between car-makers and watch-makers – including some of the most quirky and interesting, as well as the most iconic.

As fans of the brand may know, the Smart car of the late 1990s was a collaboration between quirky watch brand Swatch and German automaker Mercedes-Benz – a venture that reportedly lost $US4.6 billion before the project ended.

The Smart car brand was recently revitalised as a new joint venture between Mercedes-Benz and Chinese car giant Geely – owner of Volvo and Lotus – with the first new-generation electric car being released in limited markets in recent months.

The Swatch Smart Car watch, reference GZ154, was launched in 1997 to commemorate the opening of the assembly plant – a ribbon-cutting ceremony attended by then-French President Jacques Chirac and German Chancellor Helmut Kohl.

While the abstract dial design left us scratching…