Update: General Motors is extending its 0% financing offer through July 7 on selected vehicles. Success of the original sale, which ran from June 24-30, has led the company to continue it in the hopes of boosting summer sales and starting July off on a strong note, especially as the U.S. enters the July 4th Independence Day weekend.

Dealers saw increased foot traffic in dealerships for the duration of the sale, but some felt sales were limited due to the short time of the promotion, reports Automotive News. By extending the sales period on the back of the previous one, GM may be able to get buyers that couldn't decide before the last sale expired back into the dealership to buy a car, truck or SUV.

Original: All 2009 model General Motors cars will face a price rise of 3.5% from Tuesday, June 24. A 0% financing offer will start at the same time. Price rises have already been announced by several of GM's competitors, so the announcement was expected. The no-interest financing offer on selected models is likely calculated to bring more people into dealerships as sales slow across the market.

It's not just sales of pickup trucks and SUVs that are nosediving in the U.S. - sales of some small cars are also stagnating or trending downward, despite their relative advantage in the market. The generally poor economy is likely at least partly to blame, though some small cars like the Honda Civic and Toyota Yaris are seeing increases in sales, reports Automotive News. Another factor holding back smaller car sales is a lack of the smaller, more efficient four-cylinder equipped variants, with too many V6s readily available.

The 0% financing offer could help persuade some buyers that might not otherwise even set foot in a dealership that now is the right time to buy. With 72-month loan terms and only 72 hours to take advantage of the deal, the move could actually drum up some unplanned purchases. However, if buyers aren't able to find a car that fits their budgetary needs in terms of fuel bills, it may end up like Chrysler's "Let's Refuel America" marketing gimmick that has so far proved to have little to no positive impact on retail sales.