To find the ratio of the number of cars without a sunroof to the total number of cars, we first determine the number of cars without a sunroof.
The total number of cars is 56, and the number of cars with a sunroof is 27. Therefore, the number of cars without a sunroof is:
\[ 56 - 27 = 29 \]
Now, we have the following:
- Number of cars without a sunroof = 29
- Total number of cars = 56
We can write the ratio of the number of cars without a sunroof to the total number of cars as:
\[ 29 : 56 \]
Thus, the final answer is:
\[ 29:56 \]