Mom of 2 in a 2005 Toyota Matrix with 217K miles. Ride it out. I know another family of 4 in a Honda Fit as their main family car, and it works just fine.
Teach your kid to stop kicking, or turn kid back to RF. It's safer, anyway. Both of my kids RF to 5 y/o. If your kid can't RF in the current seat, I promise a car seat that works will be cheaper than a new car.
Ohhh this is interesting. Yeah, there is no way we could RF til even 3 years old in the carseats we have. He hit the weight/height for both where they said to switch to FF.
I hadn't thought of it before but maybe I should check with one of the agencies that does seat adjustments. I'm sure they've seen it all and might have some ideas...
I share your point of perspective (way above average boys who are avid seat kickers). The first thing would definitely be to investigate different car seats. Our convertible car seat is an absolute monster compared to the high-back booster seat our older one uses. I think we switched him to the high back booster a couple months after he turned 3, and it definitely freed up a ton of rear leg room.
That being said, your criteria are kind of limiting (mainly, the hybrid/electric preference). I think the 2 largest reasonable vehicles that would truly be an upgrade in terms of cargo volume and comfort would be a Rav4 Hybrid or a Prius V, but expect to shell out close to $18k for the Rav4 and $10k for the Prius. Most of the other electrified options (Leaf, regular Prius, Ford C-Max, Focus Electric, etc.) have less interior volume than your Fit.
Remove the electrification requirement and you'll find many more options - Mazda 5, Toyota Matrix, etc. Obviously if you venture up into the CUV (CX-5, CR-V, Escape, etc.) you'll find the most space and comfort but I have a feeling you'll not be too happy with the mileage (or the cost in most cases).
Really, it comes down to 2 things - can you successfully relocate your toddler in the car to gain interior volume?, What's your realistic use case if you can't?