$5 coins no longer appear one after the other. This makes them feel more special and gives you more of a reason to stop what you are doing to go grab them.
Carrots now spawn lower down which means building a low profile vehicle doesn't make carrots ineffective.
The friction and drag has been re-balanced so that adding height to your vehicle has the same effect as adding width. This means the choice between building high and long can be based on more interesting things like synergies between panels or play-style.
Improvements
Added lots of sound effects and reworked the sound engine completely.