I believe that's only if you use public transport through the Pass Navigo. I'm not sure individual tickets are reimbursed, and I'm pretty sure gas isn't either.

But getting 50% off of your Navigo, which is a monthly pass allowing you unlimited use of Paris and greater Paris public transports. Which is about 75 euros. So when your are subsidised by your company with respect to public transport, you have unlimited access to all public transport in and around Paris for 38 euros. Which is nuts because the Parisian public transport network is crazy (metros, trams, buses, transiliens, RERs).

you can get individual tickets reimbursed too, my mom is working part-time around Paris and she keeps her used tickets as a proof of payement.

When I was working as a consultant at Alten, in theory my gas could have been reimbursed (based on distance travelled and car horsepower), but I never tried since I used public transport during all my time there.

Only if you come with public transport. They refund half your monthly pass then.

There's also a push to apply it to bicycles, but it's not widely implemented so far.

But it doesn't apply to car commuting.