A quick Would You Rather today.
I was inspired by a teacher asking students to model airport parking as a means to get at linear equations. I thought I’d frame it similarly, but using the WYR format, because I like the WYR format.
I live a good distance away from a major airport, and I travel quite a bit for a living so I think about this all the time. I have to balance a flat, $80 fee (for both ways) vs. paying for parking (per day, the big variable here), gas, and tolls.
Enjoy!
emergent math 
Why not see the CO2 emissions too? Car sharing alternatives would be useful here for comparisons (apart of bus, taxi, etc.).
For a more advanced class, there could also be a probabilistic aspect if there is a chance that (a) your trip length might change and (b) you might want to go somewhere other than home when you return from your trip.