Your car insurance is about to get personal. And if you’re willing to let the insurers track how many miles you drive, you can save a lot of money.

The concept of paying for insurance based on the mileage you drive makes perfect sense. Currently, insurers lump you in with a demographic based on age, gender, location, marital status, driving record and the type of car you drive. All are expected to be predictors of the risk of accident and theft. But what if you find yourself in a higher-priced demographic and yet you only drive your car on weekends instead of commuting to work? With traditional insurance, low mileage is a factor that doesn’t count in pricing.

Now companies like Metromile and even big insurers such as Allstate, Progressive, State Farm and Travelers are offering products that give huge discounts — if you’re willing to insert a device in your car that calculates the number of miles you drive each month. It’s a concept that was started a few years ago and is gaining steam because fewer people are objecting to the “tracking” concept as a violation of privacy. After all, there are likely red-light cameras tracking your car anyway, not to mention your smartphone apps!

Plus, there’s a growing demographic of drivers who use their cars far less frequently, such as people who have moved back to the cities with good public transit or “snowbirds” with a car used only seasonally. Not everyone has switched to Uber or car rentals. Just as media packages and grocery shopping have become personalized through technology, now there’s a trend to personalize car insurance — and save a lot of money.

The large insurers aren’t leading the push because they currently price for the worst case. You’re lumped in with drivers who spend a lot of time in their cars, so if you’re a low-mileage driver you’re subsidizing their risk. Weeding out the least risky drivers, in terms of miles driven, would likely cut into big insurers’ profits.

That’s why a smaller but fast-growing company like Metromile has become a leader in this space. Jeff Briglia, chief operating officer of Metromile, says the edge is in the technology — not only in the tracking device but in the services the company offers based on the data. For example, the device can read your car’s diagnostic codes. So if you are late for an oil change, it can send you a message through the Metromile app. Even better, if you live in a city that has overnight parking bans on different days for things like street-sweeping or snow removal, it will send you a reminder message because it knows exactly where you are parked!

And here’s one advantage over traditional car insurance. That device that tracks your mileage also tracks your car if it is stolen! When you report a theft to the company, it will contact the police with the data to quickly locate your vehicle.

But best of all, Metromile brags that its average customer saves $741 a year on car insurance! You pay a basic monthly rate and are billed monthly for actual miles driven. If you take a long trip, there is a cap on the monthly charges, so you don’t face a sudden huge bill.

Saving money is key — but customer service is critical. The big brand-name insurers have spent a fortune in advertising to convince you that if you have an accident or if your car is stolen, they will be there for you.

Technology now makes competition possible in this area. No matter which company you use, you’re unlikely to meet with an insurance adjuster. Now you send photos of the damage to your insurer, and it will direct you to a repair shop in your area — or you can use your own. That is exactly the formula at Metromile, which has a broad network of body shops across the country.

Currently Metromile operates in only eight states: Illinois, California, Oregon, Washington, Arizona, Pennsylvania, New Jersey and Virginia. But more states will be added this year. By the mile coverage from Allstate and the other big insurers is not available in all states.

If you drive less than the average 12,000 miles per year, it might pay you to check out car insurance by the mile. And that’s The Savage Truth.