Premium class automobile has 100 million lines[1] or of that order, whereas a Boeing’s 787 Dreamliner require less than 1/10th of that. LoC is no measure of complexity of a system but it is still an indicator of how much is going on inside. So what is it that an airplane doesn't have but a modern car has?
[1]http://spectrum.ieee.org/transportation/systems/this-car-runs-on-code
* 2009 link but coming from IEEE, I believe it is credible enough.
*Not sure if it really qualifies to be Ask HN question