Of the cars in a used-car lot, 25

To find the fraction of the cars on the lot that are both gray and electrically powered, we can use the information provided.

- Total gray cars = 25
- Gray cars that are electrically powered = 13

First, we need to determine the total number of cars on the lot. However, we are only asked for the fraction of cars that are both gray and electrically powered.

To find this fraction, we will consider the ratio of the number of gray, electrically powered cars to the total number of gray cars:

\[
\text{Fraction} = \frac{\text{Number of gray electrically powered cars}}{\text{Total number of gray cars}} = \frac{13}{25}
\]

Since we need the answer in simplified fraction form, and \( 13 \) and \( 25 \) share no common factors other than 1, the fraction \( \frac{13}{25} \) is already in simplest form.

Thus, the fraction of the cars on the lot that are both gray and electrically powered is:

\[
\frac{13}{25}
\]