OP, few more things you might want to think about:
Do you have time of day billing? Or if you don't would it benefit you? It depends on the amount of power you can use during off-peak compared with what you are using during on-peak hours.
Some utilities have significant differences between on- and off-peak rates. This is to give an incentive to people to shift their usage from peak hours to off-peak hours to even out the load on the utilities generation and distribution resources. You should check it out.
If you have such rates available and sign up for time of day billing, you would want to have your car charge during off-peak times as much as possible. Since the off-peak time period may be a fairly limited time frame you may need to charge more quickly than you can with 16 amps at 120 volts, which is only charging at a 1.92 kW. Depending on how much you drive, the car may be continuously charging on a 120 volt circuit.
In comparison, a 30 amp will allow charging at 24 amps which at 240 volts is 7.76 kW. You just multiply amps times volts to get the power in watts, and divide by 1,000 to get the power in kilowatts (kW). And you need to know that any EV circuit should only be used to 80% of its capacity because they are used continuously for long periods of time.
In such situations, the savings cost in electricity may pay for the cost of installing a 240 volt dedicated circuit, whether it is a dedicated 20, 30, 40, 50, or 60 amp circuit. The savings aspect of this makes no difference if it is a Tesla Wall Connector or a dedicated 240 volt receptacle using the Mobile Connector, but be aware the maximum charging rate from the Tesla Mobile Connector is 32 amps, and the maximum rate your M3 RWD can charge at is also 32 amps.
However, the installation cost can be different as has been noted by others above since most jurisdictions now require an expensive GFCI circuit breaker for 240 volt receptacles located in garages and laundry rooms, whilst the Wall Connector requires a standard breaker. Note that the electrical code requirement for a GFCI breaker for 240 volt receptacles in garages and laundry rooms is a fairly new thing and existing receptacles that were installed before this change in the electrical code may not be set up with GFCI breakers.
Since you say you know very little about "electronics", another thing you need to be aware of is that you might be limited in what you can do by the size of the electrical service in your home. In my area most homes built since the 1970's have 200 amp service and some have 150 amp service if they are smaller. Some larger homes have 400 amp (or greater) service. Other older homes can have 60 or 100 amp service. This is a general rule of thumb, there are always exceptions.
A 2,000 to 3,000 square foot home that has 200 amp service usually has no problem adding a 240 volt 50 or 60 amp circuit for an EV as long as the home has just the normal high power 240 volt appliances such as a dryer, range (or separate cooktop and oven), electric water heater, air conditioner or heat pump, etc., but the only way to know for sure is to do a load study, which any electrician can do. Even 150 amp service can usually handle a full power 240 volt EV circuit, but in this case doing a load study is even more important. Homes with 100 amp service usually need to cut back to 30 or even 20 amp (240 volt) EV circuits (depending on the results of a load study), but any 240 volt EV circuit is better than using a 120 volt EV circuit, especially if you have time of day billing or if you drive more than about 40 miles a day on average.
Some older homes that have never been updated still have only 60 amp service. Adding a 240 volt EV charging circuit to such homes is usually not possible unless everything in the home is gas and then it might be possible to add a 15 or 20 amp 240 volt EV circuit. Such circuits should only be installed after a careful evaluation of all the components of the homes electrical service wires and panel or fuse box, etc.
I enjoy writing about stuff like this and helping people who are new to EVs, which I was just about a year and a half ago. I know this is pretty long, but I hope the information will be helpful for you.
