Xterra fuel economy :(
- Thread starter proper4wd
- Start date
The problem is weight, friction, and aerodynamics. I've kept a decent watch on my fuel economy over the last seven years and here's what I've noticed:
- When I upgraded to BFG AT/KOs I lost about 1mpg
- When I added the skids and sliders - 1mpg
- When I added the front and rear bumpers, plus winch - 1mpg
- With the RTT on, about 2-3mpg.
- I've now got an M416 that I'm hauling and that actually got me 1mpg back over having the RTT on there.
- Forgot to add that I lost another 1mpg when I switched the MT/Rs from Goodyear (stickier tires).
- And another 1mpg when I put the lift on. Sitting higher up seemed to have disturbed the aerodynamics somehow.
So yes, I went from about 18-20mpg or so to 13-14mpg, depending on whether or not I've got summer gas in there or not. There are some things that can be done, but as noted, not much. Things you could do:
- Run driving tires vs wheeling tires. Harder compounds and skinnier tires means less traction, but better fuel economy.,
- Go on a diet - pull the skids and extra weight.
- Tuners, spacers, etc - but you're only likely to see minimal gains which won't pay for themselves (especially as fuel gets cheaper).
- While maybe not driving slower, accelerating slower. Think grandma driving. Plan your stops in advance and coast as much as possible. When you're coasting you're using zero to minimal amounts of fuel.
- Keep the tires properly inflated.
- Plan your trips to minimize windshield time. No, this doesn't help the mileage but it does reduce the fuel costs because you're driving less miles. Basically, run all of your errands in a loop that minimizes miles driven.
Or, like most of us, go all Zen-like and realize that you're kind of hosed in the mpg department. I've done the trip from Columbus, OH or Detroit, MI to Moab 5 times now. I budget that this will be $1,000 in fuel and live with it. I kind of have to as I did it twice this year and would like to do it twice again next year.
Ghost65
Allergic to Pavement
Read through this whole thread with sincere interest...nice posts Jon and Robert.
Until I got to the post that discusses the theory/purpose of building/modding an Xterra for fuel economy...um what?
HOV and SUV are not just opposite in consonant and vowel mixtures...they are polar opposites on their built for "purposes."
Xterra's are heavy from the factory (I prefer stout...or husky) because they are essentially a lifted 1970's station wagon, aka: Sport Utility Vehicle, coupled with a 6 cylinder engine for power to propel all of that roof racked', dirt loving...girth.
Not to counter sink the nail any further...but your answers lie buried on the surface of this well responded to thread.
Until I got to the post that discusses the theory/purpose of building/modding an Xterra for fuel economy...um what?
HOV and SUV are not just opposite in consonant and vowel mixtures...they are polar opposites on their built for "purposes."
Xterra's are heavy from the factory (I prefer stout...or husky) because they are essentially a lifted 1970's station wagon, aka: Sport Utility Vehicle, coupled with a 6 cylinder engine for power to propel all of that roof racked', dirt loving...girth.
Not to counter sink the nail any further...but your answers lie buried on the surface of this well responded to thread.
Maddmatt
Explorer
I choose to use math to sleep better. Using your example of 1700 miles:
At 16 MPG, you are going to burn 106.25 gallons of gas. At 20 mpg you would only burn 85.
Assuming $3/gallon for easy math (much cheaper than that today, maybe more expensive tomorrow, so we'll just use $3)
16 mpg cost you $318.75, if you were getting 20mpg you would have only spent $255. You could have saved $63.75.
So multiply that over the life of the vehicle, lets say 100k miles, again just for easy math.
At 16 mpg you will spend, at $3/gallon, $18,750 for fuel.
At 20 mpg, you would spend $15,000.
So, finding some way to boost your fuel economy to 20mpg could save you as much as $3,750.
Figure it will take the average person 8-10 years to drive that much, $3,750 in savings over 8 years equals $468.75 per year. That's $39 per month. About $10 per week.
Speaking for myself, with the exception of the first gen. RX-7 I drove in high school, and that was nearly 30 years ago, I have never enjoyed driving a vehicle as much as I love my Xterra. I get the same gas mileage that my 3rd gen 4-runner got, with substantially more power, room and creature comforts. I'm happy to make a coffee before I leave the house, instead of stopping at Starbucks - to make up the difference between driving the vehicle I want vs. something lesser.
We all have our rationalizations, so your mileage may vary, so to speak - but this is what works for me.
At 16 MPG, you are going to burn 106.25 gallons of gas. At 20 mpg you would only burn 85.
Assuming $3/gallon for easy math (much cheaper than that today, maybe more expensive tomorrow, so we'll just use $3)
16 mpg cost you $318.75, if you were getting 20mpg you would have only spent $255. You could have saved $63.75.
So multiply that over the life of the vehicle, lets say 100k miles, again just for easy math.
At 16 mpg you will spend, at $3/gallon, $18,750 for fuel.
At 20 mpg, you would spend $15,000.
So, finding some way to boost your fuel economy to 20mpg could save you as much as $3,750.
Figure it will take the average person 8-10 years to drive that much, $3,750 in savings over 8 years equals $468.75 per year. That's $39 per month. About $10 per week.
Speaking for myself, with the exception of the first gen. RX-7 I drove in high school, and that was nearly 30 years ago, I have never enjoyed driving a vehicle as much as I love my Xterra. I get the same gas mileage that my 3rd gen 4-runner got, with substantially more power, room and creature comforts. I'm happy to make a coffee before I leave the house, instead of stopping at Starbucks - to make up the difference between driving the vehicle I want vs. something lesser.
We all have our rationalizations, so your mileage may vary, so to speak - but this is what works for me.
Dake21
Adventurer
Any modification you would do to your Xterra to improve fuel economy would compromise your offroad capability.
Exemple: lower your vehicule for less air resistance, get highway tires, have a different bumper ergonomy for more aerodynamics (would give a worst approach angle.)
Like others said change your driving habits and shave some weight. Maybe get rif of the spare wheels and roof rack...but then what's the point?
Exemple: lower your vehicule for less air resistance, get highway tires, have a different bumper ergonomy for more aerodynamics (would give a worst approach angle.)
Like others said change your driving habits and shave some weight. Maybe get rif of the spare wheels and roof rack...but then what's the point?
ramiromunoz
New member
Don't forget about the winter mix fuel crap we get at gas stations.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
codesertrat
Geoff
As a high horsepower industrial engine service training instructor who specializes in turbocharged spark ignited engines, I will add a few engineering related things to the discussion of fuel economy.
The measure of an engines efficiency is called brake specific fuel consumption (BSFC), which in simple terms is how much fuel heat energy is consumed per hp produced over time. All of the engine mods mentioned (CAI, exhaust, etc) will slightly decrease the engines BSFC by improving breathing efficiency, resulting in a marginal improvement in economy. Anything which can be done to decrease the pressure drop of the air into the cylinder will decrease BSFC. Include the throttle angle in this consideration, which is why overdrive and lower numerical gear ratios increase fuel economy - the lower rpm means the throttle has to open more to carry the same load, which decreases pressure drop into the cylinders and decreases BSFC. I can provide the math and dyno results behind the concept if needed.
However, a vehicle which has been modified for (or originally designed by the OEM for) off road use, is by nature going to consume a lot of fuel compared to a passenger car when driving down the highway simply because it takes more horsepower to do the same job. 4wd drivetrains are inefficient and consume hp due to all the shafts, gears, hypoid gear differentials, large tires, etc. Boxy utilitarian bodies, very tall stance, RTT's, and exposed suspension and undercarriage are horribly unaerodynamic. Strong frame, body, suspension components, etc are very heavy. Off road vehicle = high hp required to push the vehicle down the highway at 75mph. Probably 2 to 3 times as much as a typical passenger car, which means 1/2 to 1/3 the fuel economy.
A naturally aspirated, low compression, old technology engine like the Nissan VG33E in a heavy, high stance 33" tired Xterra is just never going to produce 20mpg running down the highway at 75mph. There simply isn't anything easy and inexpensive which can be done to make it better. A light foot on the throttle is the only possibility - by not asking the vehicle to accelerate quickly, the hp demand is decreased, and thus economy will show the most substantial gains. Slowing down the highway speed decreases the aerodynamic drag, thus hp demand is lowered, so better economy results.
Why do we put up with crappy fuel economy in an off road vehicle? Because a passenger car cant go the places, traverse the rough terrain, and haul the camping gear into the backcountry. Thats all there is to it.
There's no such thing as a free lunch.
The measure of an engines efficiency is called brake specific fuel consumption (BSFC), which in simple terms is how much fuel heat energy is consumed per hp produced over time. All of the engine mods mentioned (CAI, exhaust, etc) will slightly decrease the engines BSFC by improving breathing efficiency, resulting in a marginal improvement in economy. Anything which can be done to decrease the pressure drop of the air into the cylinder will decrease BSFC. Include the throttle angle in this consideration, which is why overdrive and lower numerical gear ratios increase fuel economy - the lower rpm means the throttle has to open more to carry the same load, which decreases pressure drop into the cylinders and decreases BSFC. I can provide the math and dyno results behind the concept if needed.
However, a vehicle which has been modified for (or originally designed by the OEM for) off road use, is by nature going to consume a lot of fuel compared to a passenger car when driving down the highway simply because it takes more horsepower to do the same job. 4wd drivetrains are inefficient and consume hp due to all the shafts, gears, hypoid gear differentials, large tires, etc. Boxy utilitarian bodies, very tall stance, RTT's, and exposed suspension and undercarriage are horribly unaerodynamic. Strong frame, body, suspension components, etc are very heavy. Off road vehicle = high hp required to push the vehicle down the highway at 75mph. Probably 2 to 3 times as much as a typical passenger car, which means 1/2 to 1/3 the fuel economy.
A naturally aspirated, low compression, old technology engine like the Nissan VG33E in a heavy, high stance 33" tired Xterra is just never going to produce 20mpg running down the highway at 75mph. There simply isn't anything easy and inexpensive which can be done to make it better. A light foot on the throttle is the only possibility - by not asking the vehicle to accelerate quickly, the hp demand is decreased, and thus economy will show the most substantial gains. Slowing down the highway speed decreases the aerodynamic drag, thus hp demand is lowered, so better economy results.
Why do we put up with crappy fuel economy in an off road vehicle? Because a passenger car cant go the places, traverse the rough terrain, and haul the camping gear into the backcountry. Thats all there is to it.
There's no such thing as a free lunch.