General Motors Corp.’s OnStar service will begin sending out new monthly diagnostic feedback messages for customers concerned with fuel consumption and locating ethanol stations.

OnStar, the on-board safety and security system, says the e-mails will inform drivers about their vehicle's tire pressure, E85 fueling locations, emissions and oil life. OnStar says it will begin phasing in the service throughout the year.

GM’s and OnStar’s emphasis on gasoline savings reflects the growing public angst with fuel prices, which currently average $2.99 a gallon nationally, according to American Automobile Assn.

The tire-pressure service lets consumers know if their current pressure falls below the manufacturer’s suggested level. Properly inflated tires can improve fuel economy by 3%, according to the U.S. Environmental Protection Agency.

OnStar vehicle diagnostics also will notify drivers if their vehicle is compatible with E85 fuel, a mixture of 85% ethanol and 15% gasoline, which GM is promoting as an alternative to gasoline-only vehicles.

The notices also include Web links to the National Ethanol Vehicle Coalition, where drivers can locate the nearest E85 fueling location.

The monthly feedback includes powertrain emissions data and will analyze individual driving patterns to predict when a vehicle requires an oil change.

GM’s OnStar Vehicle Diagnostics has seen more than 1.6 million enrollees since it was launched in September 2005, the company says. Onstar’s more than 4 million subscribers can opt into the new service for no additional cost.

The service already provides drivers with engine, airbag, antilock brake and other mechanical feedback, as well as reminders on scheduled maintenance.

OnStar recently participated in an incentive that capped the cost of gasoline at $1.99 a gallon for customers buying certain GM '06 and ’07 fullsize SUVs and midsize cars in California and Florida.

In the offer, which GM since has discontinued, OnStar calculated vehicle-fuel consumption for participants, who then received credits applied monthly to a pre-paid card that could be used toward the purchase of qualifying vehicles.