The monthly cost of owning and operating a car in Britain is higher than the average mortgage payment, according to auto insurance statistics released this week. The RAC Insure Motoring Index report shows that, with gas, insurance, taxes, and depreciation factored in, a car costs $806 a month. The typical monthly mortgage payment, by contrast, is just $768. Rising gas prices could push the cost of car ownership even higher in the coming year, the report says, perhaps by as much as $28 per month. The British have higher taxes on gas than most other European countries, pushing the current price of gas to $5.56 a gallon.