Ikarus C42 at about 86 knots will use 13 L/hr, for a two-hour flight, it's 26 L fuel and 8.31 kg CO2/gal avgas[1], this comes to 57 kg CO2 to cover 320 km (and this is assuming it immediately starts covering flight distance and not using gas for climbing/approach, etc.).
An average new car in the EU uses 6 L/100 km in 2019[2]. To drive 320 km, this comes to 19 L of gasoline (8.1kg CO2/gallon finished motor gasoline[1]), which is then 41 kg CO2.
Even if you had to make the auto trip 400 km because roads aren't as direct, this comes to 51 kg CO2.
Nevermind that airports are rarely your final destination, nor in the city centre like train station would be, which adds significant distance to your overall trip.
[1] https://www.eia.gov/environment/emissions/co2_vol_mass.php [2] https://www.iea.org/articles/fuel-economy-in-the-european-un...
What if there's a sogging great mountain range in the middle and I literally do need to drive 2-3x as far, because (rail) tunnels take something between 2 and 3 decades to build and won't be finished before 2040, if any are even planned to begin with?
Hmmm, in my experience, highway speeds are conducive to ICE efficiency and use less gas than city traffic stop and go results in. It also disperses pollution outside the areas people work/reside in.
- highway
- not highway, not city
- city
The 90-110km/h limits of regular roads tends to hit the sweet spot of engines more reliably than the 130+ of highways, a lot of smaller European car engines are uncomfortably close to redlining at 130+, especially older ones.
In my personal experience with both my current and previous cars, the sweet spot is constant speed about 65 to 80kph.
It does feel slow though.
As for highway speeds, cars are calibrated to have the highest efficiency at highway speeds[2][3], so per distance, most cars will do best at reasonable highway speeds.
[1] https://news.ycombinator.com/item?id=41166749 [2] https://www.researchgate.net/figure/Speed-fuel-consumption-c... [3] https://qph.cf2.quoracdn.net/main-qimg-2ddbd8f31c84cefba540d...
That said, looking at the website for the main post, I don't think that's the main use case it has in mind: top banner rotating between "Flying made easy for first-time aviators/weekend trips/avoiding traffic" or "We believe the freedom of flying is an unparalleled experience that everyone deserves access to" and "The power of flight is intoxicating".
It's great if existing use cases of GA aircrafts have sleeker/more intuitive interfaces, but adding demand in this area (more hobbyists, more rich people using it for shuttling/avoiding traffic, encouraging people to live in very remote areas, etc.) and using it as transportation-mode will unlikely ever become environmentally reasonable.