Two Convertibles with some similarities, but otherwise different in most aspects such as the modifications, starting price, horsepower, fuel economy, ground shadow size, and height. First of all, there is a notable difference in the starting price of the 2018 Porsche 911 Convertible, which is $160,900 less than the base MSRP of the 2018 Bentley Continental GT Speed. Also, the 2018 Continental GT Speed has bigger and thirstier engine; the 2018 911 Convertible gets 8.5 more mpg. In addition, the Continental GT Speed body is slightly larger than the 911 Convertible, and in addition to that, it's also taller. Among similarities are the body structure, market segment, and maximum occupancy.