If you look for maintenance free car - then none of the model is maintenance free - rather no car is zero maintenance. However, Maruti definitely has lower spare part cost and much times bigger network giving it edge over Amaze from Maintenance view
In terms of
- Power : Amaze Diesel scored ahead with 1.5 Lit Diesel Engine with 100 BHP Power and 200 NM Torque. This is much better against Ertiga 1.4 Lit with 82 BHP and 110 NM Torque
- Fuel Efficiency - Ertiga Claims a mileage of 22.8 Km in CNG, Amaze on other hand claims mileage of 25.8 Kmpl in Diesel. On overall running cost, its almost going to be same. However, on a monthly drive of 2000 Kms - you will still save around Rs. 250 - 300 with Ertiga
- Space - Amaze is a compact sedan. You will find better legroom and shoulder room space in Ertiga for 5 passengers as against Amaze.
CNG has 2 bigger challenges
A) Its not available across all parts of country and major rush in Fuel pumps in city like Delhi
B) CNG Kit optimum performance remains for first 4 - 5 yrs. Though, one ideally has to get CNG Kit checked regularly
On net on all basis - Engine performance in terms of Power and Torque as produced by Amaze - Ertiga scores good in cabin space, looks, maintenance and fuel efficiency factor. Else, if want to get away from hassle of CNG Kit Maintenance issue, delays at fuel pumps and look for powerful engine and sedan feel - Amaze could be your pick.