Unmanned, of course. Because putting living beings inside a Reliant Robin, even if it's upgraded for space travel, is just irresponsible.
In case you're not familiar with the Reliant Robin, here's a video from British motoring series Top Gear to get you started:
Now, the fascinating thing about the Kerbal Space Program recreation of the car is that not only did it make it through the launch unscathed, but it also managed to enter an orbit around Planet Kerbin.
Guess it was meant for space travel all along. Explains the terrible handling, I guess?
Z1-M4N, the redditor responsible for the build, is currently working on improving the model to make it re-usable, so it can land and take off again. Sounds like quite the task!