Get Better Model (max it), Rudder Control (1 is enough for starters), Fire Engine (1), Crane Booster, Hurricane (max it).
Other upgrades at your leisure.
Throw your plane and let it fly at "windmill height". Use fuel just to adjust height to get to the next windmill.
You won't be needing other upgrades since cranes and windmills will grant you durable speed, but you can get them while they're cheap.
As for the mystery upgrade... Your choice ;)
+ this comment if it helped you! :)
 "Endless Migration"){kind=icon}
 "Vampire Physics"){kind=icon}
 "Flight"){kind=icon}