I'm sorry, as usual I have to make things difficult.
My response is something that might not be a sequel, but a possible spiritual successor.
And that's Team Sonic Racing [https://store.steampowered.com/app/785260/Team_Sonic_Racing/], the Sequel/Spiritual Successor of Sonic and All Stars Racing Transformed [https://store.steampowered.com/app/212480/Sonic__AllStars_Racing_Transformed_Collection/]
Sonic and All Stars Racing Transformed is the best Cart Racing Game I ever played in my life. I grew up a Nintendo Kid, by the way. The 8 year old me is calling me a traitor. But I simply love it.
It was full of life. The music was BANGING. The vehicle transformations. The (albeit light) car modifications. The Power Ups. The Stages.
Oh My GOD, the STAGES. THE CHARACTERS. The whole experience dripped fun and personality. I smiled. I smiled so much playing it. I smiled in a really bad time in my life. It reminded me that there was fun.
Ever since I got a switch, I have been begging the universe for two things. Street Fighter 3rd Strike and Sonic and Allstars Racing Transformed. I got 3rd Strike from the 30th anniversary collection. and I'm happy. When the news dropped that there was going to be a new Sonic Kart racing game from Sumo Digital, it felt like my prayers were finally answered. The Details was scant, but it had Sonic in his same Kart that he had in Sonic Transformed as a cover.
I literally teared up when I saw it. I thought it was a sequel. I bought it and loaded it up, psyched that I'd finally have a Sonic Transformed on the go.
And Team Sonic was muted. All muted. With a team mechanic that isn't fun. Doesn't matter if you're in first place, if your team isn't as good as you, you lose. I still barely get what the power ups are.
Also, strangely enough as an ex-Nintendo Fanboy, I didn't play that much sonic. I'm sure the stages are great throwbacks to those who played it, but I felt nothing seeing these places.
And as you see in the ratings, I'm not the only person who thinks something is off. There are people who love this game. I get it. I'm glad they do. But this is just a shadow of what Sonic Transformed is.