SAN FRANCISCO — In one of the first real-world reports of the true cost of driving the electric Tesla Roadster, the company's deposed founder reports that it is 'something between two cents a mile and six cents a mile.'Describing his earlier reports — when he was part of Tesla Motors — as 'naïve,' Martin Eberhard recently amended his comments after putting more than 1,000 miles on his personal Tesla Roadster. The detailed report seems aimed at MBA graduates and accountants and is accompanied by an elaborate Excel spreadsheet.But, as one blogger commented about the posting, the 'simple answer is, less than gas.' As of Wednesday afternoon, AAA's Fuel Gauge Report said the current U.S. average for a gallon of gas is $3.68.'My first (naïve) comments while at Tesla were between 1.5 cents and two cents per mile, if I recall correctly,' wrote Eberhard. 'These were just based on the lowest-tier, off-peak rate. I didn't take into account the impact of domestic consumption, usage that pushes you into higher tiers or all the taxes and meter charges. I also wanted to know if Tesla's current claim of three cents per mile is realistic. For my house, it turns out to be pretty close.'He says, 'For me, it's about 3.6 cents per mile.'Eberhard reports that the car's charger 'does not have a power meter, but the car calculates kWh/mi (kilowatts per mile) for each trip (with the trip meter).'With my driving (kind of zippy, never with the hardtop on, hills and winding roads), the car seems to consume about 260-270 Wh/mi.'Eberhard, who has become sort of the unofficial Tesla Motors watchdog since his unceremonious dumping from the electric-car company, also blogs about the car's ease of use. 'It is really easy to plug in my car every day,' he notes. 'It takes about five seconds to plug in, five seconds to unplug.'What this means to you: If you can handle the Tesla Roadster's steep price tag, it'll take pennies to operate, says one of its first owners. — Anita Lienert, Correspondent