Armed only with a fold-out chair and a backpack full of food, Mr Stephens was the first person in the world to order the hotly-anticipated Model 3 on Thursday.
Tesla is expected to release first images of the car when it's unveiled online on Friday at 2.30pm AEST.
Despite the lack of pictures of the car, a line of people waiting to place their orders stretched more than 20m outside the dealership on Thursday morning.
Tesla workers are expecting significant numbers through the doors to order the car, which will retail for around $45,000 (US$35,000) when it's released in Australia in 2018.
Mr Stephens said he didn't mind spending money on a car he hadn't seen before.
"To me it's the first lower priced electric car, from a manufacturer who thinks that electric cars are the future," he said.
"In terms of the environment, it would be wonderful if we had electric cars in Sydney.
"For that reason, I don't mind spending the money for this car before it's unveiled."
He said being first in line was important, but doubted he could've lasted another day.
"I was wondering how long I could last, two days was my maximum" he said.
"I couldn't have done more than two days, I camped out on my seat and just dozed off at night. It was quite cold last night and lucky we were under cover.
Mr Stephens' son, Alex, joined his father for the tail end of the camp this morning.
The line outside the dealership in Artarmon, Sydney on Thursday, March 31 Source: SBS
He said he's proud of his father and that he shares the same passion for Tesla cars.
Australia was the first market to be able to order the model globally, ahead of its official release in the US in late 2017.
"I must say that I am proud of him, to camp out for 48 hours is a decent effort," Alex said.
A file image of a Tesla vehicle parked at a charging station outside of the Tesla factory in Fremont, California on May 14 Source: SBS
"The belief in the idea of electric cars is huge for us.
"I got here at 6am to join my dad, we are very excited because this one is a big deal."
The Model 3 is Tesla's take on an "affordable" consumer car.
Tesla has released three models since launching in 2003, including the Roadster, Model S and Model X.
The brand's entry level Model S currently starts at $91,000 (US$70,000).
