The Joss JP1 is a test prototype sports car developed by Joss Developments which never made production.

The first test vehicle, known as the JT1, was designed, engineered and subsequently launched in 2004. It was shown to the public at the Melbourne, Adelaide and Sydney Motorshows to critical acclaim, and established the company as a serious supercar operation. The prototype vehicles achieved performance figures in testing with an acceleration time of 0–100 km/h (62 mph) in 3.0 seconds and a quarter mile time of 11.7 seconds at 130 mph (209 km/h).

The Joss JT1 can be seen in the Xbox 360 video games PGR3 and PGR4 (although at that point no actual road-going car existed), as well as in Forza Motorsport 3, Forza Motorsport 4, and Forza Horizon.

Following feedback, additional external investment and other technological developments, the company embarked upon their mid-engined production version, internally code-named the Joss JP1. Production was set for 2013 with 25 produced each year at a price above $500,000. After investment ended in 2014, attempts were made to scale down to a race car version to compete in Targa Tasmania using crowdfunding.

As of December 2016, the JT1 is listed for sale on the carsales.com.au website.