While the pace car is punching a hole in the air it still takes a significant amount of effort to achieve those speeds. Just try pacing behind a fast wagon on an A road at 50mph. It's not like riding on the rollers. :-)
The reason for the shape of the bike being "unconventional" is that to keep the bike stable at that speed they've gone for a long wheelbase. It does not need to turn fast... just needs to be stable in a straight line. They've also gone for motorcycle technology (wheels and front end) as bicycle tech, especially the wheels and tyres, is just not designed for those speeds. So that also influences the design of the bike.
Not having to be "aero", much like a stayer or derny racer, also influences the position.