A new pilot program is asking New Jersey drivers to track their mileage to explore a new way of funding roads and bridges.

Officials are exploring whether a mileage-based fee would work better than a state gas tax.

“This is a data collection exercise,” said Diane Gutierrez-Scaccetti, commissioner of the New Jersey Department of Transportation. “No decisions are being made for New Jersey about how we’ll fund transportation. But without data, we can’t make good decisions.”

And to get that data, about 400 drivers are plugging a small device under their dashboards to keep track of how far they drive.

There’s an option that would allow GPS or a mileage-only option.

For three months, miles will be counted and then the device is returned.

Volunteers can earn up to $100, and they’ll find out their final mileage tally.