Should I buy a used car or new moped or used moped ?

Hey,

I'm new to Gothenburg, my wife is studying. I'm planning to earn some money by doing Uber or Foodora. To do that, what would be the best option? My maximum budget is 40000SEK. So far my thoughts are like this,

If I buy a used car,
- As initial cost is high ROI is long.
- There is a risk of breakdown as it's used.
- It's better for winter (I guess)

If I buy a new moped,
- ROI is medium
- No risk of breakdown near future
- Not optimal for winter

If I buy a used moped,
- ROI is short
- Have risk of breakdown
- Not optimal for winter

What do you guys think? Which points did I missed? What are good car/moped brand, models? If you have any related experience please share. Thanks in advance 😊