I'm a bit confused as to which gear is best for me, D or D3? Is there a difference when it comes to performance and gasoline consumption? I understand that D2 and D1 are only used for uphill climbing and engine breaking when going downhill. But what's the difference between D and D3 in terms of it's usage? I drive in an area where the roads are very bad so I seldom go beyond 60km/h. Should I use D or D3 or it doesn't really matter?