Performance
In terms of horsepower, the Vibe packs quite a wallop and will knock the Pontiac G3 down a few rungs. On the flip side, remember that high horsepower engines often command higher insurance premiums.
Handling
With their similar turning radii, the G3 and the Pontiac Vibe most certainly handle about the same into and out of tight spots.
Drivetrain
The Pontiac Vibe's engine isn't much larger than the Pontiac G3's.
Utility
Neither the Pontiac G3 nor the Pontiac Vibe has a marked advantage with respect to seating capacity.
Convenience
You will definitely have to visit your friendly gas station more often with the Pontiac Vibe than with the Pontiac G3.
Comfort
Taller drivers will considerably enjoy the extra head room in the Vibe's front cabin compared to the G3.
The Pontiac Vibe provides more head- and leg-room to your passengers than the Pontiac G3 does.
Dimensions
The G3's tank is roughly the same size as the Pontiac Vibe's, though the Pontiac Vibe's is a little bigger.
The G3 and the Pontiac Vibe compete for the same parking spaces.
Cost
Producing a precise gas mileage evaluation is so hard that some think not even the federal government can do it, but it looks as though the Pontiac G3 is the winner when it comes to gas mileage.
Regarding fuel economy, the Pontiac G3 has the Pontiac Vibe beat.
Regarding MSRP, the G3 costs significantly less than the Pontiac Vibe.
The G3 will save you a lots_of_money at the pump every year compared to the Vibe.
Warranty
The Vibe and the Pontiac G3 have the same basic after-sale protection.