The car is a 2000 Honda Insight. The transmission is failing, the battery is failing, I bought it cheaply, but it keeps carrying on. I had it running a pretty long oil fill of 5w30 conventional oil. Factory spec is 0w20. The car always got between 50-60mpg on a tank. After changing the oil with Syntec 0w20, my mileage has mysteriously improved. I don't know if this is due to other factors such as changing to winter blend fuel, or the milder weather letting me go without A/C, but I haven't seen 70mpg on the FCD before, and my mileage right now is around 71.9mpg in mixed driving. Big difference! There isn't much point to this thread other than to say that in a Honda Insight, you need to run the factory specified weight of oil to get the best fuel economy.