I think there's next to nil chance for an independent start-up to succeed, irrespective of its product.
Even in Tucker's time, the challenges were formidable. Today, the obstacles are all but insurmountable.
The entire existing auto industry is a giant cartel that's also for all practical purposes an arm of the government. GM, for example, now receives the same support from our government as Toyota and Honda do from the Japanese government. An independent/start-up would face a daunting, arguably impossible, contest with these "connected" goliaths.
Compliance costs are also something no smaller/start-up could deal with. For example, an automaker typically must destroy scores of new cars to "certify" bumper impact standards and so forth. GM, Toyota, Honda, etc. can afford to do that.
A new start-up can't.
Then there's emissions compliance. Engineering a new engine (powertrain) already involves a massive investment; then you have to not only meet current federal and state emissions laws (as determined in your labs, by testing yourself, etc.) you have to (again) "certify" to the satisfaction of the federal and state governments that your cars meet those standards before they can be sold. This involves massive expense on the order of many millions of dollars.
Even if all the above could be wished away, it remains true that economies of scale enjoyed by the majors make it almost inconceivable for a small start-up to eke out a profit.
Then there are labor issues (unions, EEOC). And local red tape for the assembly lines & factories... .
As my mobbed up friends would say, fuggedaboutit!