CUDA 6.5 with g++ does not support c++11?

I read it here that CUDA 6.5 has started support for C++11 :

http://ift.tt/1ylQ5Ir

But when I compile an example code below, I got

$ nvcc -std=c++11 cu-gcc11.cu -o test

nvcc warning : The -c++11 flag is not supported with the configured host compiler. Flag will be ignored.

cu-gcc11.cu(7): error: explicit type is missing ("int" assumed)

My setting : CUDA 6.5, g++ 4.5, ubuntu 12.04

Codes :

#include <cuda.h>
#include <iostream>

__host__ void test() {
  float a = 12.;
  double b = 3.;
  auto c = a * b;
  std::cout << c << std::endl;
}

int main()
{
  test();
  return 0;
}