Compared to all but the most efficient modern cars, motorcycles still win out on efficiency.

Most new cars are guzzlers anyhow. I really gets me worked up when I see a Chevy commercial bragging about how many of their cars get 30+ MPG. My 91 Mazda Protege got 41mpg until the day I sold it with almost 300,000km on the odometer. There aren't many cars you can buy today new which are that good on gas and aren't a hybrid.

Neither of my bikes are that good on gas but are close despite one of them being a sport bike and the other being 25 years old.

Scooters are super efficient. A small (50cc or smaller) scooter in good condition being ridden normally (and not flat out all the time, everywhere) could get 100 mpg. I've heard estimates of about 85mpg from 'real world' driving from people I know who commute on them.