Without taking a look at the existing wire, breaker box, and transformer, it's a bit hard to say exactly what the options are.
For right now, the Volt's amperage needs are minimal, even at Level 2. You can easily run two EVSE's from a single 50 Amp circuit. Depending on your wiring, you might even be able convert an existing circuit to 240 and add two NEMA 6-20 outlets for TurboCord Dual's or hardwire in two Clipper Creek LCS-20's. If you have the right gauge wire (e.g. 6-2 Copper or 4-2 Alum), you are looking at one hour of labor and $100 in parts. This get's you five (or more) years down the line and allows you to see where things are going before shelling out the big money. No breaker box drama... simple to do.
If the garage is fed with lighter gauge wire, you'll be forced to run new wire. If that's the case, I think you have three options.
1) Run one 50 Amps circuit from the main panel. You would need to pull at least one 6-2 Copper or 4-2 Alum wire. A 60ft run would be around $250 for the wire and ~$100 for tandom breakers and appropriate receptacles. Add on a few misc parts and I'd guess $500 plus labor. You are able to run two Clipper Creek LCS-20's, which are currently appropriate for your Volts.
2) Given that labor is far more expense than the parts, it makes a lot of sense to future proof a bit and pull two circuits at the same time. The labor cost stays the about same, but the wire and parts will be closer to $750. This would provide the ability to run everything up to two slightly derated 48 Amp Tesla home chargers simultaneously (running at 8.6 kW or 7.7kW depending on cable length, etc). Most newer 150-amp or 200-amp service panels (breaker boxes) should accommodate this without too much problem, but you are really pushing the capacity of the home's maximum load from the meter.
3) Add a 100, 150, or even a 200 Amp sub-panel in the garage and feed two 50 amp (or greater) circuits from there. A 100 Amp service from the existing meter would take some work, but might be done without a major reconfigured of your meter and service wire from the transformer.
Note: As of today, the largest home charging system is the Tesla High Amperage Charger, which is capable of 72 amps. Plan for two of those and you are looking at some serious electrical work, including adding a second transformer (or upgrading to a commercial transformer), adding a second meter (or replacing the current meter with a commercial meter), and pulling new service wire from the transformer to the home and/or garage. In effect, you are adding a second panel, identical (or greater) to your home's existing service. Depending on the accessibility to the pole/transformer and what is between the house and garage. this might actually be easier to do than pulling wire from the house to the garage. It's going to be expensive, but you are set for the forceable future regardless what happens with home charging.
Any good electrician can figure out your options. You don't specifically need a electrician that specialize in EV charging stations, but you do need to let then know about the max load and frequency of use. At a minimum, for today, you are looking for one 50 Amp or two 20 Amp circuits. For the future, you are looking at two 50 Amp circuits. If you are really want to future proof, you are looking at a 150 Amp (or greater) service panel dedicated to the garage.
