Hero MotoCorp Glamour

For your specific needs, a straightforward 125/160cc commuter bike would be the best fit. If mileage is the absolute top priority, then going for something in the 125cc space like the Honda Shine, Hero Super Splendor / Glamour models will be advisable. 

If you want something a little more powerful, then bikes like the Honda Unicorn / SP 160, Bajaj Pulsar N160 and TVS Apache RTR 160 4V single-seat variants are machines you should look at. 

The Avenger will be able to do what you are looking for. But being a cruiser, its ergonomics are very laidback, and its suspension isn't the most comfortable either. 

We would recommend taking a two-up test ride of each bike you consider before you make up your mind. 

From the Hero portfolio, we would recommend any of their 100cc commuters like the Splendor, Passion and HF models. If you can fit the Super Splendor or Glamour 125 models in your budget, then those are worthwhile too. All are simple, frugal and hardy machines which should likely last you a long time with minimal maintenance.

The 125cc commuter bike class is divided broadly into two groups - the traditional-looking, straightforward options and the sporty-looking, feature-loaded options. If you want something that's a 'typical' commuter bike, the Honda Shine 125, Hero Super Splendor 125 or Glamour models will fit the bill. On the other hand, if you want a commuter that has some flair to its styling and more features, the TVS Raider and Hero Xtreme 125R would be our recommendation. Both come with a single-seat option since that is something you've mentioned is a requirement for you.