Hi there, Jimmy,
I really depend on my Maps app a lot myself, and I have Siri help me if I happen to already be driving as well. I can certainly agree having to handle your iPhone while you're driving is a distraction, so let's get it working like it's meant to.
Before you start, since some of the steps I'll be sharing here can potentially result in data loss, I highly recommend having a fresh back up of your iPhone 4s.
About backups in iCloud and iTunes
If you've already tried any of the following steps, you can feel free to skip them. Test Siri/Maps after each step you try though.
Restart your iPhone, iPad, or iPod touch
Reset All Setting -- On your iPhone, tap Settings > General > Reset > Reset All Settings.
What Reset All Settings does:
Resets all of your device’s settings like Wallpaper, Sounds, Display & Brightness, Background App Refresh, Date & Time, and more.
Removes all of your previously used Wi-Fi networks and passwords.
Note: If you use iCloud Keychain, your network password won’t be deleted.
Removes your Apple Pay cards.
Deregisters your device from iMessage and FaceTime.
Removes your Touch ID & Passcode.
If Restrictions are turned on, it resets all of your restrictions.
What it doesn't do:
It doesn’t remove content stored on your device like apps, music, photos, or videos.
Your settings from built-in apps, like Safari and Mail will be the same. The settings of any third-party apps that you’re using won't be changed.
Your iCloud settings will be the same.
It won't remove any of the trust tokens that your computer is associated with.
It doesn’t reset your iTunes & App Store settings.
Your social media settings will remain the same.
Your Privacy settings won't be changed.
Use iTunes on your Mac or PC to restore your iPhone, iPad, or iPod to factory settings
Since Siri and Maps should work correctly together, the above steps will sort that out.
Have a great day!