How come Misra C checker is such a prestigious tool?
A MISRA-C checker is much more than just a style checker; it enforces a set of software development guidelines for the C programming language developed by MISRA (Motor Industry Software Reliability Association in the UK).

These guidelines are intended to facilitate code safety, portability and reliability regarding the use of ISO C in embedded systems.

There have been three versions; MISRA-C 1998, 2004, and 2012.  The latter supports C99 and contains 143 rules and 16 directives, each of which is classified as mandatory, required, or advisory.  In order for a piece of firmware to claim to be MISRA-C compliant, all mandatory rules must be met and all required rules and directives must either be met or documented as a formal deviation.

The rules are things like:


Avoid possible compiler or host differences, for example, the size
of a C integer may vary but an INT16 is always 16 bits.
Avoid using functions and constructs that are prone to failure, for example, malloc may fail.
Limit potentially dangerous practices such as non-constant pointers
to functions.
Produce maintainable code, by for example, using naming
conventions and commenting. (This would be part of the style checking the OP is referring to.)


In some ways, MISRA-C can be thought of as a safe subset of C.  MISRA-C guidelines are not only applicable to vehicular firmware, but also firmware in other mission critical areas as aerospace, nuclear, and medical.

MISRA-C compliance checking is performed by a number of stand-alone third party tools (such as PC-Lint among many others), and compilers (like Green Hills Software and IAR).  To perform MISRA-C compliance checking, both static and dynamic code analysis must be performed.  The latter in particular is fairly complex, and is probably why programs with MISRA-C compliance checking go for a premium price.  It also appeals to a fairly limited market, which also drives up the price.

There are also a set of MISRA rules for C++.