NEW YORK (MarketWatch) -- Shares of Tesla Motors TSLA, +4.42% shop up to an all-time high early Friday, as investors cheered news that the electric car maker reached an agreement with China Unicom CHU, +2.80% to have charging stations at the carrier's stores in more than 100 cities in China. The deal with China Unicom includes building supercharger stations. The stock, up 1.9% in morning trade, reached a record intraday high of $270.60 a few minutes after the open. It has gained 79% year to date, compared with an 8.1% gain the S&P 500. The U.S.-listed shares of China Unicom, the second largest mobile carrier in China, rose 3.5% to a 2 1/2-year high. Separately, China is weighing a new tax on gasoline, to help fund efforts to make electric cars more palatable, according to a report in The Wall Street Journal.