The V8 doesn't seem to be very sensitive to changes in driving habits. My last car would get anywhere between 23-40 mpg, depending on how I drove, the load in/on the car, weather, etc. In my 4runner I seem to get 16-20 no matter what (unless it's extremely cold out).
Here's my Fuelly:
4runner (Toyota 4Runner) | Fuelly
Any mod on its own might not make a measurable difference, but I'm hoping that small gains will add up. There's a nice list at Ecomodder (
65+ Vehicle modifications for better fuel economy - EcoModder.com). This guy claims to be getting 28 mpg hwy in his V8...
How to get better MPG in a toyota 4runner - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com
Here are some I've considered:
I keep my tires inflated around 37 PSI, and the ride is noticeably harsh but it doesn't improve mileage much (1 mpg at best).
The roof box doesn't seem to have a big effect, maybe -1 mpg. It's quick to remove when I'm not using it.
I would take off the roof rack, or at least the crossbars, if it was easy, but it looks like kind of a hassle. Maybe I'll do it for the summer. Or maybe I can make some more easily removable crossbars? Maybe just modifying the covers to extend the slot all the way back would work.
Next oil change I plan to use 0W20. Totoya recommends 5W20 now, as an alternative to 5W30 for our engines, and 0W20 has the same weight at operating temperature but better viscosity at startup temperatures. I don't know why they don't recommend their own 0W20 in the service bulletin, but it may be because of cost (6.5 quarts of their synthetic isn't cheap) or because theirs is even more optimized for efficiency than off the shelf oil (Mobil 1 is nice and cheap, and it's what I would use anyway if I was using another weight, so no additional cost for me) that has to work in a wide range of vehicles. I don't expect to see much gain, except for short trips. I'll also do synthetic oil in the differentials one of these days.
When I do the timing belt if I do the water pump too, I'll add a block heater. The engine seems to burn extra gas while it's warming up to warm up faster and meet emissions faster. In the winter a block heater should help reduce that, plus it will heat up the interior faster and clear the windows faster if they are frosty. I might install a battery charger wired to the block heater circuit, too, to reduce load on the alternator and extend the battery life. Electricity is generally cheaper/cleaner than gas (though maybe not if gas prices keep falling). It would nice to have the seat heater come on when the car is plugged in, too!
Next time I need wipers I plan on getting beam-style ones. The lower profile should reduce drag a bit, and they won't freeze up as easily in the winter.
I probably won't do any major aero mods because I prefer to keep the stock look. Plus I got this truck to drive off road, so I don't want to do anything to limit its capability. Notable aero problems on the 4th gen are the spoiler, everything underneath, and the huge side mirrors. I'm thinking some skid plates might help with aerodynamics, unless the added weight negates any benefit. An air dam might be better since a smooth underbody is apparently not ideal. In my state, side mirrors are not required as long as you can see out the back. Various mirrors inside the car, or the anytime backup camera mod could be used in addition to the rearview mirror. I like the running boards, but I wonder if removing them would reduce drag a bit?
I plan to add an override switch to keep the A/C from coming on when the defroster is on. It's so dry in Colorado that I hardly ever need it. It's nice to have a few days a year in the summer, and when it's raining and the windows get foggy, but otherwise I rarely need it. Much later down the road (when the truck is at least 15 years old), I might remove the A/C completely, mainly to save weight since it's just another idler pulley when it's not running. It would be interesting to remove the power steering, too, but it sure it nice to have when going off-road.
There's not much I can think of to save weight, and I'd even like to add some sound deadening material.
The V8 seems to be designed for power and torque, not efficiency. Moving a 4runner around at a constant speed uses so little power that it must be running below it's peak efficiency. Typically low RPM/high throttle is good, but if the engine is too big for the vehicle or if the transmission thinks it knows better than you (I suspect we have both problems) then the engine won't be working as efficiently as it could.
It would be nice if we had Variable Cylinder Management (VCM), but I've read nothing but bad things about DIY VCM. It would be nice if the V8 had 2WD mode for efficiency and donuts, but there's probably no easy way to add it. I don't think 2WD mode helps much, but it may be a small gain that helps in combination with other things.
I doubt exhaust mods do much. Whenever I see (hear) a vehicle with loud exhaust, I notice that it isn't accelerating any faster than the cars around it, despite making more noise. (I also notice that a lot of people with lifted trucks have tires that are too bald to ever go off road, and many people with hi-lift jacks attached to their vehicle have no jack points except the trailer hitch.)
