Wifes 03 Grand Vitara gets worse mpg than my Z06 Vette??

Is this normal? The truck is an V6 auto with about 8000 miles on it. Definitely needs a 5th gear as it is spinning too high on the highway but the power is nice. I doubt she gets much better than 15mpg in town.

i have a standard vitara with a 4cyl. 5-speed with a best mpg of 28, but i don't drive any faster than 65mph. That sounds low for a v-6 but I would see if anyone else posts with a GV is getting the same results.