Ok... played it. The car physics are fantastic and biggest fun in the game.
The game itself could be fun, but for now I think you tried to make it too realistic what I think is boring.
Endgegner is right, that the clouds kill the frame rate. You can have as beautyful clouds as you want, if killing the fps like that itīs useless.
For me it would be much more fun if the gameplay would have more design. THat means:
-the cloud in the first mission is always positioned in a far distance and I have to reach it before it disappears. The faster I am the better cloud fotos I can get. For the fastest time I even can get lightning fotos.
- I can drive across the whole country, but off the road its getting bumpy and if cops get me I loose money or time or the game ends.
- On the way are specials to get faster there, like natural jumping ramps over obstacles like fences and dustbins.
- Other obstacles could be forests
- On the way I would also have to avoid flying around dust bins, barrels, wood beams and such stuff
And for good fotos I get money to buy better cars, cameras with zoom and girls

Just my oppinion, I hope it helps.
In later missions I have to get a cloud which is far away and flying away, and if I drive into too many obstacles will loose it. And for final missions the player could be chasing hurricanes/tornados.