Hot Wheels: Highway 35/Acceleracers (found work on animated film; early-mid 2000s)
In 2003, Toy Maker Mattel celebrated the 35th anniversary of their world famed Hot Wheels toy line with the release of a 2 hour CGI movie entitled Hot Wheels Highway 35: World Race. It was released on DVD and was later aired on the Toonami Saturday Video Entertainment System programming bloc.k The film, accompanying video game and toyline were a smash hit and ensured a sequel two years later in 2005, as a series of TV films aired on Toonami as Hot Wheels: Acceleracers, which involves some returning characters and new characters fighting against the evil Robotic Racing Drones in mysterious alien worlds known as Racing Realms.
Despite Mattel's intentions of the line being apart of a "aging up initiative" for the Hot Wheels line, many older fans of Highway 35 and various casual viewers loathed it for the darker tone in the story, the convoluted broadcast time and feeling it lacked the heart of Highway 35 (including Toonami themselves, going as far to referring the show as "Mattel's Bionicle"). Along with poor toy-sales and Mainframe's budgetary problems that led to them shutting down and reform as Rainmaker Entertainment, the show ended on its 4th episode The Ultimate Race with a cliffhanger.
The Hunt for The missing Hot Wheels Promo clip
In mid 2016, a redditor on the r/Acceleracers subreddit named Sun619 told the subreddit that he had found a promo on YouTube that made him think Acceleracers was continuing via Warner Brothers (who had distributed the films back when they were producing episodes). When others asked Sun619 for a link, he said he couldn't find it again and that the video had been taken down shortly after it was uploaded.
For a while, people doubted the legitimacy of Sun619's comment until June 30, 2017 when another r/Acceleracers redditor named kevinm0388 had gotten in contact with former writers and Mainframe animators about the matter and confirmed that such a promo did exist and was made for Warner Brothers and Mattel roughly in lat 2005 to early 2006. and upon the revelation that Acceleracers action figures were to be made featuring the characters that Sun619 mentioned being in the promo (including RD-K1 leading the Drone, and Banjee Castillo, a character who was once long thought dead in the show, being alive on the Silencerz team), thus leading people to believe this was the Promo Sun617 had allegedly seen.
According to Rainmaker Studios, the only way they can release the promo is if Mattel approved of the release and the toys were turned into a McDonald's toyline. When asked about releasing the promo, Mattel they reiterated the same thing Rainmaker said and didn't elaborate further.
On January 2nd, 2018, test footage for Acceleracers was shown on a Vimeo portfolio by a studio called "DQ Productions". This video showed off previously unknown scenes and models, including Mark Wylde, one of the shows characters driving the car Reverb in the Water Realm and through a city.  At the time no one was sure if this was indeed the aforementioned test footage
On January 3rd 2018, Discord User ReeceTheR asked one of the former animators on Acceleracers William Lau about info regarding the unmade films of Acceleracers.  He provided info that a McDonalds toyline called "Hot Wheels Stunt Strikers" was originally meant to feature planned Acceleracers vehicles and also mentioned that the executive producers told them to simply call the line "Hot Wheels Strikers".  He said that was all he knew about the lines future.
On January 27th, 2018, Discord user DaimosZ asked William Lau if the promo was a direct sequel to Acceleracers that concluded the show's story arc or was a whole other series all together. Hard replied that it was indeed a hard reboot and that due to internal changes in Mattel it got cancelled altogether. He also mentioned his memory was foggy so it is possibly it could have been a sequel to Acceleracers but he cannot remember exactly if that was the case. . This debunks Sun617's comments as being fake.
Around that same time, the Hot Wheels Discord discovered that Sony was once thought to be working on a 5th and 6th movie. Sony owned the rights to the soundtrack and the soundtrack had 2 documents for two albums with the Acceleracers branding.  Warner Brothers was still releasing the Acceleracers films as late as 2012 in their 4 Kids Favorites DVD packs, rendering the theory false..
Unresurfaced Highway 35 Extended Footage
In addition, episode 4 of Acceleracers prequel Highway 35 had a rare VCD release in Southeast Asia that contained extended and deleted scenes from the episode. Some scenes have resurfaced in Spanish, including an extended intro that features the drivers introducing themselves to the audience. One scene has yet to resurface in any language is a short clip where a character named Dan Dresden says "Yeah, I'm willing to put aside competition...for now."
- The Toonami Wikia article on the block. Retrieved 22 Nov '17
- The Toonami Wikia article on Hot Wheels Acceleracers. Retrieved 22 Nov '17
- A YouTube video explaining the negative reaction of Hot Wheels Acceleracers. Retrieved 22 Nov '17
- Sun619's Reddit post. Retrieved 22 Nov '17
- kevinm0388's Reddit post. Retrieved 22 Nov '17
- An Acceleracers animator confirming the existence of A Promo. Retrieved 22 Nov '17
- A Hobbydb website listing the SDCC 2005 action figures. Retrieved 22 Nov '17
- Another image of what could have been the McDonald's toyline. Retrieved 22 Nov '17
- the DQ Entertainment test footage Retrieved 04 Jan '18
- First picture of the conversation between Reece and William Retrieved 04 Jan '18
- the confirmation of the alternate title Retrieved 04 Jan '18
- The interview between William Lau and DaimosZ Retrieved 29 Jan '18
- the US Copyright offices records for the Sony Acceleracers connection Retrieved 18 Feb '18
- DVD cover for the 4 kids favorites release of the Acceleracers movies Retrieved 18 Feb '18
- The Accelepedia article on the deleted scenes. Retrieved 22 Nov '17