Here are some of mine suggestions what you can vote for implementing into early stage of game.You can add your further suggestions as well.
Also, instead of voting you can put here your order of first implementations into game "on the fly".
Cars, and overall drive physic and handling
56% (18 votes)
Tracks and Circuits
41% (13 votes)
Online Social media connections (Google+,Facebook...)
3% (1 vote)
Car design and liveries
0% (0 votes)
Total votes: 32