You need SpintiresMod.exe (Mudrunner Plus) to play the map because the height map is above what the game by itself allows.
The link to it is in the discription.

You can not drive on the map because you are above the map so you can not move. If you look at the map you will see that you floating.

Unfortunately as map makers build larger maps using dev tools, both in area and in height, you will be unable to play them. This is a passive benefit to having it. Another somewhat passive benefit is a longer wench line (you set the length in the settings). I like that I can change night to day with it.
Supposedly Mudrunner 2 is suppose to be 64 bit instead of 32 bit. Dev Tools gives map makers and players the 64 bit advantage now.

Too much trouble, don't want to get it

...it's in the first line of the description!

Do you have dev tools (spintiresmod) Sergeant 118? If not there is a link to it in the description.
But I would think a player without dev tools could download and play the map, until they hit their 64 height limit.

Why can't I download this map and drive away?

Let me know if there is anything odd or off about the map. I went over it with the editor, and driving around it, numerous times and kept finding little things to change/correct. There are likely still things I didn't find.

Нам не очень охото гадать с текстурами (We do not really want to guess with textures). The only odd texture in the map is the gravel roads that are on the climbs.
машины тупо не двигаются (cars don't move stupidly). Gravel does tend to move cars 'stupidly'.

Darren; Perhaps you and your dad can work together to complete it, it would be very hard for one person to do.

You're welcome Happy Days; enjoy

Oh SHoeInTurd, not another one. I'll be up all night on this one sean300bc. Thanks heaps mate.

Now that is a work of art! I'll send a link to my dad...he'll love this. Thanks for continuing to share your hard work.

машины тупо не двигаются!

Нам не очень охото гадать с текстурами!