Chrysler is extending its offer of $2.99/gallon for gas through July 7 due to the success of the campaign — and other automakers have followed suit, reports MediaBuyerPlanner.

The automaker's "Let's Refuel America" campaign, which offers consumers $2.99 per gallon of gas for up to three years with the purchase of select models.

"Let's Refuel America" boosted showroom traffic by 10 to 20 percent in some regions and website activity has soared 25 percent, writes Brandweek.

The campaign was expected to end June 2, but will be extended to July 7.

Suzuki is running a similar campaign and has also seen enthusiastic response. Its "Free Gas for the Summer" offers buyers zero percent interest and free gas for three months — instead of cash rebates — on vehicles purchased between May 1 and June 30. Daily sales were up about 9 percent during the first week of the promo. 25 percent of buyers reportedly take the financing and free gas offer.

Kia has a different take on helping consumers deal with soaring gas prices. Its television ads focus on the inherent gas savings of Kia models.

Two years ago, GM offered a $1.99-a-gallon fuel discount for buyers of selected vehicles.

Gas mileage was cited the number-one influencer of vehicle purchases by 34 percent of auto buyers, according to a May 2007 poll by J.D. Power & Associates. That number is expected to jump in this year’s poll.

The promos arrive at a time when automakers are shifting ad spend away from TV to digital advertising. But the efforts may not be dramatic enough, according to a recent study by BIGresearch.

For example, only 17.5 percent of General Motors customers say television affects their auto purchase, while GM spent 40 percent of its $3 Billion+ ad budget on TV ads in 2006 (proportions similar to other leading automakers’), according to the BIGresearch analysis.