I've been a profitable part-time Realtor for over a year and I have never been in a situation where having a shitty, ugly car would have lost me business. Ever.
I've never had a client in my car - it's less and less common with all the paranoid people these days. More and more, they meet you at showings.
There are many niches in real estate and they don't all require you to haul people around town in luxury. For example, since I am also a real estate investor, my primary customer is MYSELF. I turned a profit in my first year (paid for licensing and all first-year fees, board dues, company costs, etc) just through investment deals when my partnership bought rentals. When DW and I downsized from our fancy townhouse and made it a rental, my "buyer's agent" commission on our new $120K purchase alone put me in the black.
But even if you don't have the "self-service" advantage, you can carve out a niche with like-minded people who aren't swayed by dumb superficial shit like how your car looks, or if you even showed up in one. MMM types. Cash flow investors. Rehab specialists. They're out shopping and they're smart enough to look past appearances. If you're knowledgeable and can help people identify good investments, a good chunk of them won't care about the car thing.
And of course, there's the "friends and family" angle. If I'd had time to handle the ones who were interested in the last year, I would have made *at least* $10K just from friends around town who heard I got licensed and wanted to give me a shot when it was time to buy or sell. The only reason I didn't was I'm still working 3 other jobs and I literally didn't have time.
Being licensed in real estate also gives you much of the required knowledge to be a paid property manager, which can be a good gig. You don't have to have the license to do it, but it shows that you have Fair Housing Act training and other vital knowledge to ensure you follow the laws while holding tenants to their lease requirements.
All that doesn't mean it's the time for you to go into real estate, and if - as you said - you have a tendency to jump into things - I would suggest taking your time and doing due diligence. I would suggest going and talking to a broker about your intentions, and see if they think you'd be a good fit. They generally love talking to new people, especially prospective agents, and most will be willing to help clarify expectations and outlook for you.