I'd like to see the range indicator go away entirely and just have a rate of closure indicator in it's place.
Here are three varients of an idea that I've posted before. Each of the three lines is a varient. In the first line pluses, minus' and equals symbols are used to give some indication of closure rate. In the second line a bubble that ranges from black filled to white filled with the brighter color indicating a faster closure rate supplies the data. In the third line a red dot that becomes progressively more transparent ranging from solid red for very fast closure to completely transparent for a rapidly receding target.

Each column represents the same data. Here is an example of what the data could mean:
1) The target is being approached by greater than 135mph.
2) The target is being approached by greater than 45mph but by less than 136mph.
3) The target is being approached by greater than 15mph but by less than 46mph.
4) The target is being approached by greater than 5mph but by less than 16mph
5) The target is being approached or escaping by less than 6mph.
6) The target is escaping by greater than 5mph but by less than 16mph.
7) The target is escaping by greater than 15mph but by less than 46mph.
8) The target is escaping by greater than 45mph but by less than 136mph.
9) The target is escaping by greater than 135mph.
(It looks a lot better in .bmp format, curse .jpg corruption and .bmp file size)