Gives between 7-8 in city and 10.5-12 on highway. Not much difference in fuel economy of both. My Vigo gives 7.5-8 and Onvincible used to give 7.6-8.2.
Overall Vigo champ is a very decent car if you don't compare it with imported vigos. Maintainance cost lower than imported one and newer model in same price. Imported models, especially invincible, on the other hand are more comfortable and powerful, but they have a higher maintainance cost, more prone to issues and will be older.
It's tough to choose for me as both have their pros and cons, but if I can find a relatively newer model of invincible with low mileage and good comdition I would go for that, even though it's old. But the only reason for that is more powerful engine.