The insurance industry is busy telling us that it has teamed up with environmentalists to clean the air by cutting insurance premiums for drivers who spend less time on the road.

The reality is that they want to monitor your driving electronically, and charge you more if you decline.

"Pay-as-you-drive" insurance that charges low-mileage drivers less does make sense. It's called for in the landmark Proposition 103, passed by voters 20 years ago. But a bill headed through the state Legislature makes drivers' privacy the cost of lower insurance rates, and gives insurers fresh ways to charge you more.

State Farm told the California Department of Insurance last month that insurers should be allowed to collect "time of day," "days of the week," "type of road," "where miles are driven," "speed" and "aggressive maneuvers (hard stops, starts, or turns)." Progressive Insurance already sells a plan in several states that uses wireless devices to track not just mileage, but time of day and "how aggressively you drive."

Will an insurance company decide that nighttime driving is riskier (as Progressive already does) and try to charge higher rates to the janitor and nurse who work the third shift? Or that a few quick stops last month make you too "aggressive" a driver? It's almost certain that they'd surrender details about when a car was driven if subpoenaed by a spouse's divorce attorney.

Adding injury to insult, this tracking technology won't even work with older cars, whose drivers will get dinged to pay for "discounts" to customers who agree to being monitored.

Proposition 103 back in 1988 said that miles driven must be the second-most-important factor for auto insurance rates. (The most important is driving record.) The insurance industry spent years fighting against such emphasis on mileage. Not until 2006 did then-Insurance Commissioner John Garamendi pass rules requiring insurance companies to comply with the law. Those rules went into effect this month.

Now, suddenly, the companies who fought this idea for two decades have claimed it as their own. They're taking the opportunity to reach for other unfair advantages with the help of the state Legislature.

The industry-backed legislation by Assemblyman Jared Huffman, D-San Rafael, would allow different (and certainly higher) prices for drivers who don't sign up for insurers' mileage verification programs.

Yet Progressive's technology is only compatible with cars made after 1996. GMAC's mileage plan limits participation to consumers who sign up for GM's OnStar service. It is not offered with the cheapest GM cars, or cars made before 2004, and drivers must pay a minimum $199 for a yearlong service contract.

Supporters say that, since these plans would be voluntary, anyone concerned about fairness or privacy could simply opt out. Drivers of older cars, often low-income, are automatically denied even that "choice."

People who don't sign up for the program would pay for other drivers' discounts, because the insurance company has to make up a rebate by charging someone else more.

In California, where privacy is protected in the second sentence of the state Constitution, people are rightly going to be concerned about insurers' use of information they collect in our cars. No one should have to pay more for auto insurance in order to protect their privacy. A fair "pay as you drive" program would offer the option of a physical odometer check.

The insurance companies' bill comes to the floor of the state Senate next month. Legislators should reject this industry attempt to charge people more because they cannot, or choose not, to verify mileage with an electronic tracking device.

Insurance Commissioner Steve Poizner can get it right for California drivers. He began regulations on the issue of miles driven last month.

The commissioner should require "pay as you drive" policies be accessible to all drivers, and limit to one thing – mileage – the information insurance companies are allowed to collect.

Carmen Balber is a consumer advocate at the nonprofit Consumer Watchdog, 1750 Ocean Park Blvd., Suite 200, Santa Monica, CA 90405. Reach Balber at (310) 392-0522 or carmen@consumerwatchdog.org.