Short answer: no to a second vehicle, yes to a second (or third) driver.
Our car insurance products are built as a three-way relationship between you, your cell phone, and your car, so each policy is tied to a single insured vehicle, and we're not able to add a second car to an existing policy.
What we can do is add extra drivers to that one policy, so everyone who might get behind the wheel of the insured vehicle is covered.
If a family member has their own car, the best setup is for each of you to have your own Just Insure account, with your own email address and phone number, so you can both take advantage of our low-priced telematics pricing. Your family member simply downloads the app and sets up their own account with their own email, phone number, and vehicle. You'll both be covered driving either car, as long as you're a licensed driver.
Whichever plan you're on, "Per-mile" or "Unlimited miles," we think you'll see the same savings our other customers do.