I got both, so I can give you some answers.
But these answers will be about my subjective experience.
I am not the kind of person who cares about dimensions, but about the feeling of driving.
The S1 is more Spartan.
It’s a hand-made car and you can see it n the details. It’s simpler in its construction and nothing is hidden when you open the front cover.
Which you cannot do on the S2.
There you can see the cooler, the battery and some other stuff.
I found it cool to see the inside of the car on the front too.
Since the battery is upfront, you have more room in the trunk. The trunk is a perfect cube; you don’t have the extra volume coming up like in the S2 trunk.
The cockpit is more extreme: No airbags, sill covers are minimal, no carpet anywhere: just the aluminium chassis and two seats. Really cool.
The S2 cockpit looks likes like a real car. The S1 is a no-bullsh*t race-car for sure. That means no A/C.
Ventilation is not so good in the S1. It works, but there is no opening towards the passengers. Just the windshields and feet ones.
The soft-top is a pain is the @$$ to take down. It’s basically a camping tent. Leaving the car open all day long and close it for the night is best.
Weight is lighter and you feel it’s 100kgs less. Great street kart.
Engine is “only” 120 hp. It was enough for me.
The S2 seems more stable at high speeds. I was scared driving 180 km/h in the S1 (the car could go 201 km/h).
In my S2, I don’t notice I am already 190km/h (God bless german highways!).
Rover Engine is the big weak-point.
The cooling system actually is: the cooler is too thin, ventilator too weak, the water pump too weak and the temperature gauge starts too late.
Staying too long in a traffic jam will kill the engine for sure (ask me how I know. 2 times).
People with money used to put a Honda Type R in the car and upgraded the cooling system.
S1 has a different “face”. It smiles to people and people smile back at it.
Its sympathy capital is WAY bigger than the S2 that looks like a mean machine.
Everybody loved the S1. EVERYBODY. No jealousy, no negative feelings from anyone. Never in 5 years.
S2 looks as expensive as a Ferrari and people get mixed feelings when seeing it.
Side view of the S1 is very impressive. The S2 has classical door designs. But the carving of the S1 door is unique on the street.
The @$$ of the S1 is sexy. I mean it. Look like it has been sculpted by an Italian sculptor
My ideal car would be the S1 with front of the S2, and Toyota engine.
S2 looks great in every colors.
S1 looks like a big toy in red, or yellow. Colors that make it look sexy are limited.
Old school colors work very well on it (British green with cream interior, Silver with red interior and son on).
S1 had colored softtops. That was cool.
S1 only has black tops.
I miss my S1, not the ****ty cooling system and Rover Engine.