FOSTER CITY, Calif.—It's been a few weeks now since a Bay Area startup put a digital license plate on my car.

So far, nobody seems to have noticed. I haven't yet been pulled aside by police or civilians asking what it is. At first glance, this electronic device looks exactly like a traditional, stamped metal license plate. The new digital plate has the same scripted CALIFORNIA icon up top and uses the exact same size and font to show the numbers and letters.

But in actuality, what I have is an "Rplate," a $700 plate-sized Kindle-like screen on the back of my car—high-contrast grayscale e-ink and all.

The device also contains an RFID and GPS chip that allow me to see where my car is at any given moment, to voluntarily track my trips (think an Uber or Lyft-style ride map), and to even optionally display DMV-approved customized messages in a small font below the plate number itself. (Mine currently says "Watch for Cyclists," although during the NBA Finals, I had "LET'S GO WARRIORS!")

Were I an actual paying customer, I'd be paying $7 per month in a service fee, too, mostly to offset the data connection to Verizon. The one-time $700 price tag alone is a bit high for me. (If you think I should be paid more, feel free to email my boss.)

To be clear, I have a loaner model, and by the time this story comes out, I'll soon be sending the plate back to the company, Reviver. The model I've been using is one of the first 1,000 such plates that are legally out on California roads right now.

More are coming, according to Reviver CEO Neville Boston, who told me at his office recently that in addition to being legal (and commercially available) in the Golden State, the plate is likely coming soon to Arizona, Texas, Florida, and Washington state at their state agencies' discretion. Reviver is pushing other states, including Georgia, Illinois, Michigan, Colorado, and New Mexico, to follow suit in the coming months.

Still, after my experience of a few weeks, there's no clear and compelling case to be made as to why most of us non-rich individuals need this fancy plate. Also, there are still unanswered questions about its security and what it means to voluntarily hand over so much personal location data to a single company.

But why?

Why would someone pay so much when conventional plates work well and don't cost nearly as much? In part, to mitigate theft. In a sense, the Rplate is a modern-day LoJack, which still makes a radio-based recovery system that dates back to the 1980s. But the Rplate does more than simply emit a homing beacon. The goal of the plate is mostly to enhance convenience. Imagine a near-future where you can update your registration and pay for tolls and parking all through a unified platform via a single smartphone app connected to your plate (a "platform that enables you to do everything in one place," said Boston). Plus, what if you could put silly images on your plate (or maybe sell ads) while your car sits idle in a parking lot?

At least for now, you can't display whatever message you like. Reviver only allows the Rplate to display messages that have been pre-approved by the DMV.

Boston not only wants the Rplate to help its own drivers; he also wants it to transmit important data to other drivers, like Amber alerts, Silver alerts, weather alerts, and so on. Plus, he said, it would be an "always-on Waze." And speaking of the DMV, the plate could also potentially be a way for a DMV to monitor future road usage.

What if you paid road taxes per mile driven?

Sitting in a conference room in this mid-Peninsula town just up the road from the heart of Silicon Valley, CEO Neville Boston explained that, while the Rplate is very new on California roads, it's been in the works for about a decade.

He said that the origins of the company go back to 2008 during the global financial crisis. That's when Boston began having a conversation with a friend who worked in the California state government.

"We were talking about resources that the state was underutilizing," he recalled. Boston learned that, because the gas tax intended to pay for transportation infrastructure had not gone up in a decade, "then the value of those dollars [is] precipitously going down," as he explained to Ars.

The California Legislative Analyst's Office had come to the same conclusion just a year before, noting, "The current state gas tax rate (18 cents per gallon) has been in place since 1994. Since then, inflation has eroded the value of per-gallon gas tax revenues by 29 percent, so that 18 cents is worth less than 13 cents today (in constant dollar terms)."

(If we skip ahead in time to 2017, we see Gov. Jerry Brown sign into law a new gas tax that raised the state's cut by $0.12 per gallon. Electric car owners aren't exempt, either: starting in 2020, they'll have to pay an annual fee of $100.)

Boston felt that there had to be a better way to essentially charge heavy users of roads more. Reviver—then called Smart Plate Mobile—was founded in 2009, soon after this conversation with his government friend.

"You should be charged based on how you use the roads," Boston said. "Our platform supports the ability to do that... What I'm about is working to solve real problems with technology."

The company's first prototype, a heavy, bulky item, was built in 2009. Beyond getting the hardware right, the company had to make sure that the plate was legal in its home state.

In 2013, Boston and his cofounder at Smart Plate Mobile, Mike C. Jordan, successfully lobbied Sacramento to pass Senate Bill 806, which allowed for a "pilot program... to evaluate the use of alternatives to stickers, tabs, license plates, and registration cards." Smart Plate Mobile changed its name to Reviver later that year, and its patent was issued in 2015 (similar patents have been issued to many others in recent decades for similar electronic license plates). A 2016 law, SB 1399, extended this pilot program deadline to January 1, 2019, with a report due to the legislature due by July 1, 2020.

As Ars reported back in 2013, the bill raised some eyebrows among privacy advocates, including the Electronic Frontier Foundation.