Honestly, the progress in this game is too slow. Currently, there are only 2 ways to get Car Souls; timewarp and racing. According to my calculation, you can only get max 154 souls by using timewarp but you have to get all the achievements and I doubt you can get them all in one day play. The other way to get Car Souls is by racing but you can only race once every 4 hours. I'd suggest change the time to 5 mins for a month (don't forget to scale the other numbers as well). 20 mins for a month is just too long for an idle game.
I like the pace myself and I probably won't make it faster as it is. It is not a game you play in one go for a few hours but more something you play daily for a few hours. And with the offline progress points you can spend the time how you progress like you want. Also you probably shouldn't look at car souls that much. The game can be finished without spending even one car soul. They are only an extra for people who played it a while and want to start again with an increased speed.
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I like the pace myself and I probably won't make it faster as it is. It is not a game you play in one go for a few hours but more something you play daily for a few hours. And with the offline progress points you can spend the time how you progress like you want. Also you probably shouldn't look at car souls that much. The game can be finished without spending even one car soul. They are only an extra for people who played it a while and want to start again with an increased speed.