I Lyft my M3 have been for the past six months - here are some takeaways from my experience:
1. As many ppl have said, you need to be aware of how the insurance works. When you're not in driver mode, you're on your own insurance obviously. When you're driving and have a rider, you're on the ride-share companies insurance. When you're in driver mode, but don't yet have a fare, you're in a gray zone. Some insurance companies have a special rider for this period. For me, it adds $16/mo, but it's worth it IMO. But I think if I'm ever in an accident with my M3 - that will be the end of ridesharing for me. I'm gambling for sure.
2. The ride-share companies insurance probably really really sucks...I hope I never have to find out. The Lyft deductible is $2500. This is obscene and IMO should be illegal. IMO the deductible should be matched to what you carry for your own insurance. For many people that drive their own car part time, a single minor accident will wipe out many months of "profit."
3. Lyft allows the M3 to be used for "Lux" rides, and I think "Lux Black" if your car is black. But only accepting Lux rides will drastically cut down on your income in most markets (I tried and only made 1/4 of what I made accepting any ride type).
4. It's great fun to "evangelize" for Tesla, but don't expect too much. The vast majority of riders don't care about your car one way or the other. Only maybe one out of 20 will actually be interested to learn about the car. From the rest you may get a compliment or or question and that's about it. Even this will decline once Tesla's become more prevalent obviously.
5. The doors on the M3 are a pain for riders - the back doors especially. With the front doors, if you press and release the button, the door can still be opened...it has "popped". Not the case with the back doors - you have to HOLD the button and open the door. And then there's the tricky pop-out handle. All-in-all a manageable pain, but a pain none the less.
6. Don't expect higher tips when driving the M3. I saw no difference going from an old beater 328i to the M3.
7. The inexpensive "fuel" changed the way I feel about ride-share diving significantly. Inevitably you will end up far from home at the end of a day. Nothing is a beating like having a sh!tty day with little profit, and then having to waste another gallon or two getting home - further eroding your meager earnings. The M3 changes that equation completely...I know that long drive is only taking a few pennies of "fuel" and is not putting me closer to an oil change. It's liberating.
8. It's baaaaarely enough $ to be worth doing. Someone else on this thread said that people that drive their own cars are basically extracting value from their car, not really making money. That's exactly correct IMO. But the M3, with the lower fuel and maintenance costs (knock on wood) might move that need juuuuuust barely over the profitability line. We will see.
(8a. As an aside, I'm certain ride-share companies are aware of #8 - their business model is based on people who are willing to 'donate' the largest asset of their business - the vehicles - essentially for free in exchange for returns well below minimum wage.)
9. It's a fun hobby (if you're not anal)! Don't ever quit a day job to drive for Uber or Lyft. But if you're easy going and looking for a (mostly) entertaining way to spend some time and make some "walking around money" - then I recommend it!