[TampaTundra]

4x4 weighs more so only by a little. When in 4x4 it will burn more fuel. But the 4x4 on the tundra is not a full time 4x4 or all wheel drive system. You switch it in and out of 4 hi/lo. But even in 2wd in a 4x4 it may add a little resistance and rotational weight that could affect mileage.

With wheels and tires bigger normaly drops mpg. But that said getting smaller wont help either. Has to do alot with weight, wheel weight and tire weight. Getting the X-sp package may help a little because its a thinnner lower profile tire mainly for street compared to the Michelin/ BF Goodrich tires on the other models that are a heavier tire for all terrain.

The 5.7 gets a hair better mileage but you gota act like there is an egg on the gas pedal and smoothly roll into the throttle. I have driven around town before and been amazed how little fuel I have used and I was conciously driving fuel conservatilvely but still keeping up with traffic and all. Then ran it out open out of a few lights and a few speedy passes and such and ha the needle will respond accordingly.

In my truck when I drive from my house in Tampa to college in Boca, its far south-east and around a 3 1/2 hour drive all at highway speed, I average 75-80 and get 19-20 mpg. You can notice a difference when you push the speed up only to around 85-90 your mileage does decrease a good amount.