I am getting ready to buy an Xa. I have looked at all the other super compact cars like the fit and yaris but I really like the Xa and I dont see them much. My wife is japanese and really wants a small car but I am just excited about the gas milage. My weekend car is a Twin Turbo 300zx so Im not looking for a lot of power from my Xa. What I am looking for is some modification I can do to get better gas milage for the Xa.
I guess my first question is what helps gas milage and what hurts it? I have heard that what you do to the intake side helps gas milage but what you do to the exhaust side hurts gas milage, excluding major modificaiton such as turbos for obvious reasons. Is this true? I would prefer replies from people that actually know what they are talking about to respond due to this topic because I can see many people who think they know the answer due to having heard some mechanic give a similar response.
Finally what I would expect to be good mods would be:
- Intake
- Iridium plugs (what plugs do you recomend?)
- Grounding kit (more efficient fuel burn)
- Underdrive pully (less drag on the engine)
- Plug wires (more efficient fuel burn)
If I am wrong on any of these or you know some more please tell me. Like I said if something like a cat-back exhaust will make my car a bit faster but hurt my mileage I am not interested. Thanks for the help and I look forward to joining the comunity!

Intake and exhaust should give you better gas milage, the engine will breath easier making more power and taking less effort for it to move the little xa. I would go for exhaust, Intake, Throttle body spacer and Pulley. Btw there are no plug wires on the xa or xb they have direct coils on top of each plug kind of a sweet idea. On another note you mite want to look into light weight wheels to help the gas milage. Thats my .02 cents

Break the engine in with light throttle use but rev it a little too - makes a big difference - you want to polish the bores - more air in the tires and check out the link under my signature. I average over 40mpg in my xB with NO engine mods.

Intake and exhaust should give you better gas milage, the engine will breath easier making more power and taking less effort for it to move the little xa. I would go for exhaust, Intake, Throttle body spacer and Pulley. Btw there are no plug wires on the xa or xb they have direct coils on top of each plug kind of a sweet idea. On another note you mite want to look into light weight wheels to help the gas milage. Thats my .02 cents I wasnt aware that they have direct fire ignitions! That is nice, my Z has that. I dont think a throttle body spacer would do anything for gas milage. I messed arround with intake manifold spacers on one of my last cars and basically all it does it keep the IM/TB from being heat soaked which will let the car run cooler for longer. It also gives you a few more RPM quicker due to the longer runners, but I dont think this would give you any gas milage

You have a plastic intake manifold - not much you can do to improve its function - it stays cool already and the throttle body is the air flow sensor so don't mess with that. You don't get good mileage at Full Throttle so making any changes that improve flow at full throttle will not have any effect other than emptying your wallet. Lower friction and add a few psi (5-10) more to the tires is about all you can do and keep it polished or waxed and clean on the outside. If you want to really save some money after the breakin change to Synlube and then you can forget about oil changes and get the friction reduced as much as is possible in one shot.

www.Synlube.com

what type of plugs do you recomend? Iridium or platinum? If platinum what kind?

Haven't used Platinums in a long time but back when you could actually buy them the Champion plugs were very good - really thin electrode and wide heat range. I hear the Iridium plugs work well also but haven't changed a plug in about 15 years or so - my last car ran the original plugs for 90806 miles and then junked it only gapping them a few times during their entire life. I used to get over 50mpg in that 1994 Geo Metro 5 door.

lighten up.

Intake and exhaust should give you better gas milage, the engine will breath easier making more power and taking less effort for it to move the little xa. I would go for exhaust, Intake, Throttle body spacer and Pulley. Btw there are no plug wires on the xa or xb they have direct coils on top of each plug kind of a sweet idea. On another note you mite want to look into light weight wheels to help the gas milage. Thats my .02 cents I wasnt aware that they have direct fire ignitions! That is nice, my Z has that. I dont think a throttle body spacer would do anything for gas milage. I messed arround with intake manifold spacers on one of my last cars and basically all it does it keep the IM/TB from being heat soaked which will let the car run cooler for longer. It also gives you a few more RPM quicker due to the longer runners, but I dont think this would give you any gas milage

Well there is a T.B. spacer out there that does spin the air coming.. It has a vortex type of design machined in it mite help might not. It helped my dads 4.0L jeep and my buddys expedition now whether or not it does help our little 1.5L I do not know. It was just a thought that passed though my head thought I would throw it out there.

what type of plugs do you recomend? Iridium or platinum? If platinum what kind? I would recommend Iridiums. I use them on my 2 of my motorcycle and my last car. They seem to burn cleaner. My bike would stink to the high heavens of gas while it was idling but since I changed to them, I don't smell the gas anymore. The car seemed to idle smoother and as for the gas milage on either, I didn't notice either of them go up??? So you can change them for the peice of mind that you wont have to change them for a long time....

Intake and exhaust should give you better gas milage, the engine will breath easier making more power and taking less effort for it to move the little xa. I would go for exhaust, Intake, Throttle body spacer and Pulley. Btw there are no plug wires on the xa or xb they have direct coils on top of each plug kind of a sweet idea. On another note you mite want to look into light weight wheels to help the gas milage. Thats my .02 cents I wasnt aware that they have direct fire ignitions! That is nice, my Z has that. I dont think a throttle body spacer would do anything for gas milage. I messed arround with intake manifold spacers on one of my last cars and basically all it does it keep the IM/TB from being heat soaked which will let the car run cooler for longer. It also gives you a few more RPM quicker due to the longer runners, but I dont think this would give you any gas milage

Well there is a T.B. spacer out there that does spin the air coming.. It has a vortex type of design machined in it mite help might not. It helped my dads 4.0L jeep and my buddys expedition now whether or not it does help our little 1.5L I do not know. It was just a thought that passed though my head thought I would throw it out there. I dont think you are talking about a "spacer" but rather that insert that spins the air. I too have heard mixed replies on that. Im not going to even spend the money on it. Thanks for the idea though.

I am running NGK Iridium plugs in my xA....I never noticed a mileage gain, but I'd get them just for the smoother idle.....

As much as Toyota has worked this engine, I don't see any places left to find any huge increases in mpg's....

there are always areas for improvement. You have to keep in mind the audience car companies are trying to hit. They dont want to add $40 here and $200 here just to bump the HP or MPG by a few points. Some consumers such as myself on the other hand would. Thanks and I will look into getting the iridium plugs.

intake = less gas mileage
think more air = more gas = more power (not more power = less gas) because the computer has to make a balance a/f mix unless u can fool the computer but ud be driving with a yucky air/fuel ratio (hahhahahah the tornado things mess airflow up so supposedly u get better gasmileage because restricted airflow)

exhaust is kinda mixed reviews

the spark plugs help with better burn (doesn't matter what kind. the kind u buy = the lifeexpectancy)(the 2+tips supposedly help because of better burn but really gas only needs a spark)

better plugwires just help insure current to ur plugs

grouding kit helps ground ur car really its just electronics (better boom for your radio)

definately the pulleys (lighter rotating mass) if you dont mind taking shots elsewhere like ur ac/heater/alternator

definately lighter everything though wheels/tires whatever.
if u put (i dont remember what chemicals but i think its) nitrousoxide in ur tires, it will help keep ur tirespressure consistent and not expand or shrink to much from the heat or cold n also it doesn't leak out as fast
- (in my theory) higher psi = better gasmileage but not as good grip (cant confirm this; again theory)

tb spacers - the only way spacers help is by lightening ur wallet.
although a better flowing engine like a polished engine helps

Nitrogen in the tires
Tire pressure I know helps I just don't know exactly how much but I can see a difference when only one tire gets low so it does have an effect.
I hear the grounding makes the engine run smoother ???

Nitrogen in the tires
Tire pressure I know help I just don't know exactly how much but I can see a difference when only one tire gets low so it does have an effect.
I hear the grounding makes the engine run smoother ???

i had 1tire that leaked alot cuz the kids around my neighborhood thought it was funny to put a nail in my tire so it kept leaking and everymornin it would droppsi alittle and i remember i ran with about 20psi for a week (i normally run 40-45psi *warning*dont copy me make sure to check what YOUR recommended psi; i'm running bigger tires allthewayaround) on average my mileage on a full tank is about 330ish can get up to 360 but that week i ran 240 i tink mayb 260. sooo i got it fixd

for the tCs the grounding just helpd with throttle response and electronics really haven't heard about anything else.

i know i got a tC n all but if something happens *knock on wood* the xA is definately what i'm gonna drive hahahahhah dont tell

Nitrogen in the tires
Tire pressure I know help I just don't know exactly how much but I can see a difference when only one tire gets low so it does have an effect.
I hear the grounding makes the engine run smoother ???

i had 1tire that leaked alot cuz the kids around my neighborhood thought it was funny to put a nail in my tire so it kept leaking and everymornin it would droppsi alittle and i remember i ran with about 20psi for a week (i normally run 40-45psi *warning*dont copy me make sure to check what YOUR recommended psi; i'm running bigger tires allthewayaround) on average my mileage on a full tank is about 330ish can get up to 360 but that week i ran 240 i tink mayb 260. sooo i got it fixd

for the tCs the grounding just helpd with throttle response and electronics really haven't heard about anything else.

i know i got a tC n all but if something happens *knock on wood* the xA is definately what i'm gonna drive hahahahhah dont tell

Your secret's safe with me....

intake = less gas mileage
think more air = more gas = more power (not more power = less gas) because the computer has to make a balance a/f mix unless u can fool the computer but ud be driving with a yucky air/fuel ratio (hahhahahah the tornado things mess airflow up so supposedly u get better gasmileage because restricted airflow)

exhaust is kinda mixed reviews

the spark plugs help with better burn (doesn't matter what kind. the kind u buy = the lifeexpectancy)(the 2+tips supposedly help because of better burn but really gas only needs a spark)

better plugwires just help insure current to ur plugs

grouding kit helps ground ur car really its just electronics (better boom for your radio)

definately the pulleys (lighter rotating mass) if you dont mind taking shots elsewhere like ur ac/heater/alternator

definately lighter everything though wheels/tires whatever.
if u put (i dont remember what chemicals but i think its) nitrousoxide in ur tires, it will help keep ur tirespressure consistent and not expand or shrink to much from the heat or cold n also it doesn't leak out as fast
- (in my theory) higher psi = better gasmileage but not as good grip (cant confirm this; again theory)

tb spacers - the only way spacers help is by lightening ur wallet.
although a better flowing engine like a polished engine helps
I have to disagree with just about everything you stated above except the spacer comment and weight comment. Cars are tuned from the factory rich. Adding more air to the combustion mix does increase gas mileage. Now some cars may react different but as a whole intake will give you better gas milage. Plugs will also give you better gas milage over all due to the gas burning more efficiently, it is not just a spark. If you have ever ran old plugs you would understand. Better wires just magnifies this. Grounding wires help by reducing electrical resistance, do a search and you will understand better. I am not sure what you meant by the pullies and taking shots with ac/heater/alternator...I have run several cars with pullies and never noticed the slightest change, but that could just be me.

TB spacers will help with performance but not gas.

Im not trying to argue with you but I am not new to cars at all and you are stating a lot of misinformation.

I have never heard a pulley make losses in ac/heater/alternator unless it is smaller then the stock one in which case why would you buy it unless you are gunna race?

Im not trying to argue with you but I am not new to cars at all and you are stating a lot of misinformation.
discus away u've back up ur points instead of calling me an uneducated ricer so no heat taken i'm always trying to learn and understand. please take my info with a grain of salt.

Cars are tuned from the factory rich. Adding more air to the combustion mix does increase gas mileage. Now some cars may react different but as a whole intake will give you better gas milage.

i understand the a/f mix and that the electronics goes for optimum and see ur point, but personally with two cars and a truck and also reading many other topics. yes i've read many others that say it helps with gas mileage but with my personal experiences and watching afew friends i still believe it decreases.
removed the silencers on my tC airbox and saw (on average of driving over 4months *note:work=delivering pizza and yes i drove the same never, really never reved over 3rpms) a drop in about 1-3mpg but felt alittle more push on the first half of the rpm range. but then of course 1-3 is not that significant but its not a gain either
also a galant buddy wanted to check if restricting air helps his gasmileage so he cut a bighole in his stock airbox and put his aemshortram inside for about two months (idk how he drives) he showd around an increase in about 1-3. in my galant i had 24-26mpg and droped in a generic cai and it went about 21-25 and some1 gave me a fpik k&n shortram and put that on 22-25 but i didn't take accurate measurements just every here and there soooooo can't use this (same with my truck)
again as u stated different cars react differently


Plugs will also give you better gas milage over all due to the gas burning more efficiently, it is not just a spark. If you have ever ran old plugs you would understand. Better wires just magnifies this.
i see ur point here too. i understand replacing parts and efficiency helps. first to wires. better wires really just help prevent against failing and voltage weakening. and really is needed if u have an upgraded ignition system. i see where it can help but really i cant justify the spending. now if u bring up heat understandable but i doubt ur engine is running too hot.
now with plugs. i did say better burn (i guess i didn't clarify efficiency enough). i'm still at a mix about plugs only because more tips = better spark better burn but more tips = more shielding for the spark against the a/fmix. but also gas really has a low spark rating to ignite soo why would gas not burn inside a chamber? that and alot of the spark plug co. say can help with mileage but they only say this if u replace a toreup1 (like u said)


I am not sure what you meant by the pullies and taking shots with ac/heater/alternator...I have run several cars with pullies and never noticed the slightest change, but that could just be me.
as Team7 stated the reason to get an underdrive (scion04xb usually meaning smaller/lighter)it is less rotating mass so generally less strain on the engine so the engine doesn't work as hard to turn the "accessories" hence underdrive
i'm amazed u didn't notice. ur "accessories" work less so put out less soo if u dont notice just be careful ur cooling system for ur car takes a hit (well if u change this pulley out) so ya. it does help from wearing stuff out soo theres a plus. of course ive never ran aftermarket pulleys soo i cant say from personalexperience


Grounding wires help by reducing electrical resistance, do a search and you will understand better hahahha i guess i didn't clarify but ya thats what i meant by grouding. but still dont see how this helps gas mileage

and for the offtopic:
tb spacers please inform me on how it improves performance. i've read many people have bad experiences on the dyno with these except i have read afew v6s n v8s that have had good dyno experiences but they rn't 4bangers
http://www.scionlife.com/forums/viewtopic.php?t=70165&postdays=0&postorder=asc&&start=100
(pg6towards bottom) no gains; in fact a loss. this is only one of course so if u have something that disputes please inform me


i'm not new to cars either. i know i'm young but have had a share of experiences probably not as much as u my friend but enough to know to do research before doing anything and question everything (yay i'm that _______kidinclass that questions everything :rofl: ) and definately check the dynos

I guess you have most bases covered. I would add, make sure the Intake is a Cold Air Intake and every now and then give the engine some really hard driving to avoid any carbon build up ( a few hard acceletaions should do the trick, and if you see dark exhaust fumes when you do it, it means you did it right, now if it continues with the smoke, then something is not right :nails: )

Good luck.

Other than making sure your tires are properly inflated and the AC is off, the best fuel economy mod is the driver. Drive slower, accelerate slower, maintain momentum. I get 30-31mpg in mostly city driving short trips with the AC on. I could easily drop that to 27 or so if I drove more aggressively. Likewise, I could probably up it to 33-34 if I relaxed a bit.