I know nothing about the details of your situation, but this doesn't sound likely to be a wise move.

Living in a car rather than the cheapest accommodation you can find means (leaving aside the issue of romantic/sexual relationships, though you should reconsider whether burning your bridges there is really likely to be best for you):

• More money, but not hugely more money unless you're somewhere stupidly expensive like San Francisco. (In which case you should consider moving rather than living in your car.)
• Sleeping in the car rather than in a bed: you will almost certainly sleep worse (hence, be less effective in the daytime) and will likely be setting yourself up for back problems later on, as you say.
• Nowhere to work: I guess your plan is to work in cafes or something, where there is noise and you're likely to have to spend more on drinks than if you worked at home. And this works only for some categories of work.
• Nowhere to store clothes so you will probably look scruffy all the time. Fine if your experiments on novel consumable services/products never requires you to go in person to see potential customers or business partners, not so good otherwise.
• Nowhere to bathe or shower or even wash but presumably there's some workaround for that (but I expect it will also cost money).
• You need to have the car eliminating a different way of saving money (which may or may not be viable depending on where you live).
• Possible difficulty with law enforcement because AIUI sleeping in a car in a public parking space is actually illegal in many places.
• No postal address which may again be awkward for some business purposes, for buying things online, etc.
• Nowhere to store substantial numbers of books which you may or may not care about (maybe the cool kids are using ebooks for everything these days).
• More risk from crime -- someone can steal your actual home if you do this, and other less drastic kinds of crime are also more of a risk.

Those seem like substantial drawbacks. If you have the sort of skills that give a real prospect of success making "novel consumable services/products", can't you rent somewhere cheap and pay for it by doing some sort of freelance work a day or two a week, and have a better quality of life overall?