Not bad
Firstly, great job. Its nice and easy to navigate and you even have a spiffy logo.
But there are some bits of annoyance ingame. Things such as overtaking, it is slightly realistic as you say, but for example when on a straight and you are trying to overtake to the left or right of the racer in front, he tries his darndest to let you ram on his backside, ruining your front wing. If in real life, he would have to submit to officials regarding his actions, correct? Overtaking in corners is fine.
The pit stops were hard to learn, but nothing wrong with that.
If possible, a map of the course would be good.
Great game, to bad its a demo version. Maybe if it was full version you'd get full marks ^_^