I have not done this myself, but it appears possible with some limitations. See the linked article below.
A typical GPS antenna has ~30dB of gain, but even this is not enough to get a spectrum plot capable of characterizing the signal. The author in the article uses 60dB of gain through active antenna and additional LNA and just manages to get the signal above the noise floor. Being that you want to measure inside your vehicle, there will be additional attenuations from the chassis.
On the spectrum analyzer side, you will want to make sure the receiver is configured for maximum sensitivity and a low RBW. You also need to make sure no signals exceed +20dBm into the front end of the receiver with that much gain. An RF limiter or filter might be necessary.
https://www.eetimes.com/testing-gps-receivers-with-real-world-data/
I hope this helps.
