[brian_]

I like the four-motor approach.

On the other hand, the description of the proposed project is just about the most complex type of electrified vehicle (series hybrid AWD), and the expectation is for industry-leading range... in a vehicle not designed to be a hybrid and not designed for efficiency. It would probably make sense to start with something much simpler and less ambitious.

Just one technical detail note: solar panels on motor vehicles are not very useful - they just don't produce enough power to be worth the weight and complication.

 

[brian_]

I'd like to achieve:

• 250miles per charge,
• <=80mph
• ...

That's a start on performance requirements. To determine motor power requirements, you would also need to decide on your acceleration and grade-climbing targets. A vehicle which can eventually get to 80 mph on flat ground with no wind, but takes an hour to get there, and slows to 20 mph while climbing even a gentle hill, would probably not be acceptable.