You're off a good start! The driving feels good: nicely responsive & arcade-y forward momentum and tight turning (maybe a tiiiny bit too tight at higher speeds -- a little sliding would be nice).
I'm a little worried about the scope your page description sets up, with semi-open-world elements + upgrades + jrpg elements + content for missions & an overarching narrative (+ AI and polish) to do in 2-3 weeks as a solo dev. I wonder if it might be better to pick just one (or maybe 2) of those that most appeals to you for the next week, then for the second week consider whether to add another from that list or further develop what you already have. The driving & weapons already feel like a pretty good foundation on their own!