Steermatic averages between 10.5-12lm/l in city driving. There are lots of goodies that never came in the i-dsi inc. optitron gaugaes, 7-spoke alloys, different interior trim, 1.5L VTEC engine, switches on the steering to change gears and a transmission that allows you to drive the car in 6 different modes:
- D Auto
- S Auto
- D Manual (you shift using the steering buttons)
- M Manual (ibid)
By looking at your profile, I'm presuming that you are 20 years old. If you can get your hands on a clean, low milage steermatic that has never been used on CNG then go for it bro. But that's just for you. As for your mother, a vario i-dsi or a 09 i-vtec city will serve the purpose equally well.