"Modern" suv's are unibodies without live axles. You are never going to keep up unless you force induction. Instead of worrying about reducing burden just perform preventative maintenance. 4runners go high mileage with little failures i wouldn't worry too much at 170k.

You get tired of not reading the answers that fit your narrative. People make jokes because it's an absurd endeavor for a vehicle you plan on using practically. You want to remove 400lbs from the truck say goodbye to your entire interior, hood, roof rack, running boards, skid plates, tow hitch, and possibly your rear hatch. Even then I doubt it will weigh 400lbs. Just sell your truck and get something that's more too your liking. This is silly.

@Steve Theodore

Just to further clarify the point.

Your 4th gen weighs 4280lbs aprox. You are asking to remove 10% of the vehicles overall weight and still have something that can be used as an suv.

For anyone curious, the crossbars from the OEM rack weigh 5.5 pounds when removed. This is for a 4th generation 2008 model, so your mileage may vary on a 5th generation model.

remove all the JBL speakers and run a cup holder Bluetooth boombox

Learn how to Hypermile. Probably the best chance you got.

You bought the wrong vehicle. The 5th gen 4runner is an absolute pig, riding on an ancient chassis, archaic drivetrain and rudimentary suspension setup. It will always handle poorly on pavement no matter how much weight you are able to pull off it. Simple fact, the concept of a performance 4WD body on frame truck is just silly and useless.

Having said that I do own a "car based performance suv" but it at least gets decent gas mileage (28mpg) and handles like a sports sedan. I would even be comfortable taking it on a racetrack. A 4runner will never get remotely close to that no matter how hard you try.

Reducing a vehicle's weight by 100 pounds typically yields a 1-2% gain in fuel economy. So you'd be hard-pressed to achieve any meaningful savings going this route on a family road trip.

As others have pointed out, correct tire inflation and moderation in speed and acceleration will have much more significant effects. Proper maintenance can also yield good gains:

• Replace a dirty air filter and clean your mass airflow sensor.
• Clean or replace corroded battery cables so the alternator doesn't have to work as hard.
• Make sure your wheels are aligned and the tires are balanced.
• Make sure your brakes are properly adjusted and your calipers aren't sticking to avoid drag.

If you've done all this and still need to save more fuel, start drafting everyone in front of you!

'08 Toyota 4Runner aero mods = 14% better fuel economy! - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com

Here are some aero ideas but not good data.

That dude is HARDCORE!

even at 400 pounds lighter a 4runner probably still wouldn't be competitive in efficiency and performance to a comparable unibody SUV. weight reduction seems like chasing ghosts for this platform. the more realistic approach would be to minimize weight gain wherever you can when modding (lightweight wheels, aluminum armor/bumpers, winches with synthetic rope etc)

Hoping that everyone reading this thread realizes it's only a day dream. I can recognize the folly in the amount of work it would take to achieve that dream in practice. That being said, it's just the way I operate and I'm hard wired to consider weight reduction and performance in any vehicle that I own.

Took some more weight off my '03 today, scraped the frame (again) and got another 1/4 lb of rust off it.

That's what we refer to as asymmetrical weight reduction!

This, too. The 4.0 is notorious for fuel mileage dropping like a rock the higher over 60 mph

And the school bus seats.