Ok, for those who played through the game a dozen times already but forgot to save their character and are tired to finish the Championship again just to unlock the vehicles, here's a quick guide how to edit your savegame;

You need:
Notepad++ (the version 6.6.6 works fine with the Hex Editor plug-in)
Hex-Editor Plugin for Notepad++ (you find it under Plugins-> Plugin Manager-> Show Plugin Manager , select Hex Editor (tick) and Install) (Restart Notepad++! You don't need admin rights in case it's asking, just deny)

And in the folder \Codemasters\Insane\ the file player00.chp

Drag it into Notepad++, go to Plugins->HEX-Editor->View in Hex or press <Ctrl>+<Alt>+<Shift>+<H>

(Just in case you messed around with the HEX-Editor options: 8-bit <-[this is the important setting], Hexadecimal, Big-Endian, Column-Count: 16, Address-Width: 4 is enough)

OK, quick introduction to the savegame:
Basically it's only the race scores and a counter how often you tried each race, starting with address 30.
There are 5 classes, the first one has 9 races, the second 12, the last three each 15 races.
The highest score per race is 10, which is in HEX 0a. This is the value you want to set to get every track and vehicle unlocked (you need 660 points in total for the last vehicle, the Speeder).

In case you want to enjoy the cutscenes where you win each class championship and unlock extra tracks and vehicles - well, you need to leave one race at 0 then and finish it manually.

So, here are the values: set those to 0a

#NNN gives the row number, the number in brackets is the column address. The row number is actually base 16 in positional notation (you have 16 columns) - the exact address thus is row number + column address, eg Class 1 first race of each map: the exact addresses are 30 34 and 38

Class 1
#030 (0) (4) (8)
#050 (0) (4) (8)
#070 (0) (4) (8)

Class 2
#230 (c) #240 (0) (4) (8)
#250 (c) #260 (0) (4) (8)
#270 (c) #280 (0) (4) (8)

Class 3
#440 (8) (c) #450 (0) (4) (8)
#460 (8) (c) #470 (0) (4) (8)
#480 (8) (c) #490 (0) (4) (8)

Class 4
#650 (4) (8) (c) #660 (0) (4)
#670 (4) (8) (c) #680 (0) (4)
#690 (4) (8) (c) #6a0 (0) (4)

Class 5
#860 (0) (4) (8) (c) #870 (0)
#880 (0) (4) (8) (c) #890 (0)
#8a0 (0) (4) (8) (c) #8b0 (0)

This is basically enough, but you had to start each race and quit it (you don't need to finish it) to make it count.

To avoid this you can set the following values to 01:

Class 1
130 (0) (4) (8)
150 (0) (4) (8)
170 (0) (4) (8)

Class 2
330 (c) 340 (0) (4) (8)
350 (c) 360 (0) (4) (8)
370 (c) 380 (0) (4) (8)

Class 3
540 (8) (c) 550 (0) (4) (8)
560 (8) (c) 570 (0) (4) (8)
580 (8) (c) 590 (0) (4) (8)

Class 4
750 (4) (8) (c) 760 (0) (4)
770 (4) (8) (c) 780 (0) (4)
790 (4) (8) (c) 7a0 (0) (4)

Class 5
960 (0) (4) (8) (c) 970 (0)
980 (0) (4) (8) (c) 990 (0)
9a0 (0) (4) (8) (c) 9b0 (0)

These values state that you participated in each race once and finished it with 10 points (what you set above to 0a).
Don't forget to leave one race in each class at 0 to get cutscenes, of course the same races you chose above.

Almost done. All you need now is to set the points you obtained in each class and the number of races you did.
First the number of points (if you leave one race at 0 in each class choose the number in square brackets!)
5a(HEX) = 90 (Decimal) , 9 races with 10 points each
78h = 120d (12 races with 10 points each)
96h = 150d (12 races with 10 points each)

or in case you leave one race at 0 the values are 50h,6eh and 8ch (80,110 and 140 in decimal)

Here you go:
Class 1 230 -> 5a [50]
Class 2 43c -> 78 [6e]
Class 3 648 -> 96 [8c]
Class 4 854 -> 96 [8c]
Class 5 a60 -> 96 [8c]

And the number of races: (again, use the number in square brackets if you leave one race each class for manual winning)
Class 1 234 -> 09 [08]
Class 2 440 -> 0c [0b]
Class 3 64c -> 0f [0e]
Class 4 858 -> 0f [0e]
Class 5 a64 -> 0f [0e]

Finished!

So, pretty interesting stuff.
The whole savegame is basically only this. At the beginning there is the player name saved and your last car. That's it.
Each class has 3 sections for the number of tries and points, each section being a tournament mode. The map(landscape) is the position in each section, eg. map 1 is the first position in each section, map 2 the second and so on.
You can see that each class section is 20b bytes long,
Class 1 from 02c to 237
Class 2 from 238 to 443
Class 3 from 444 to 64f
Class 4 from 650 to 85b
Class 5 from 85c to a67