I dont own a 1.8 Vtec so I cant say abt fuel consumption though Ive ridden in a friends Vti Oriel Prosmatec here in ISB city and the ride was EXCELLENT. Much better than my 03 Vti and far way better than the Altis!
The gears (A/T) shift very smoothly in the 5 speed A/T 1.8 i-Vtec.
Suspension wont be an issue, fuel consumption, maybe.