Reuters: Owners of gas-guzzling cars could be paying 25 pounds ($50) a day for the privilege of driving them in central London from October if mayor Ken Livingstone decides this week to go ahead with the plan as expected. Livingstone, who floated the idea over a year ago, is to announce his decision on Tuesday. It is part of a package of measures that Livingstone, who has made the environment a central plank of his tenure and who is facing a tough re-election battle in May, may bring …