you know kosi, i don't know what you have in your car, but it COULD be weight, wise.... JL audio/Kicker stuff is pretty hefy in weight.... i'd bet it's probably all that weight you're lugging around? unless u have mroe stuff in the car.....the more the weight the less the MPGs...also, the wheel setup too! if you're riding on 18s or anything bigger than OEM, of course gas mileage goes down =]

 

ehh.. trunk doesnt have anything in it yet but a few rags and a little tool kit for small projects...
I dont even have a spare in the trunk.
so weight isnt the issue here.

the 3GS rims dont feel that much heavier than the stock wheels. they actually feel pretty light.

 

Probably been covered in the first 4 pages, but i'll put it all in one place:

-Change air filter
-Keep up on oil changes
-Keep up on trans fluid
-Keep up on diff fluid
-Make sure thermostat is good
-Clean/Replace air filter
-Clean MAF (be careful!)
-Clean TB butterfly and surround
-Check/replace spark plugs
-Check/replace o2 sensors
-Inflate your tires 3-5psi past recommendation

Aside from that, it's all about driving style. Don't jump off the line, don't pedal the hell out of the car, and use the cruise control as much as possible, even on a back road if there's no traffic in front of you (cruise won't activate below 30mph though).

People say that pulling into parking spots so that you don't have to back up will save you some gas, but I don't see it.

Also, if you're sitting at idle, and will be sitting for more than 1min, shut the car off. It takes the average car 1min worth of fuel at idle to start back up again.

IIRC, the L7 is a heavy freakin sub. That's also going to affect your mileage, having all that extra weight in the car. When I first got my 300, I had to carry my 2-12" JL audios in the trunk for a while until i could find a place to keep them. Once they were out of the trunk, I saw a 2-3mpg improvement doing 70% city and 30% highway. For reference, my subs weighed about 80-100lbs.

 

^^ thanks for the rundown...

I also made sure to not over do it with the sound system I just want a lil thump... Im only getting an 8 inch L7 (smallest one) just so that it wont hit me too hard when it comes to weight.

 

i would consider that one lightweight sub, it's like 5lbs or something, and it hits unbelievably hard, rattling the roof and everything

 

yeah im gonna jus keep it at 1 8 inch sub... and call it a day

 

one 8" sub.....thats not enough although i doubt i'll be getting the 19 Mpg im getting now once i install this


[/QUOTE]

 

whats the specs on that?

 

RE Audio XXX 12"

Product Dimension
Mounting Depth - 12.75"
Mounting Hole Diameter - 11.5"
Overall Diameter - 13"
Bolt Hole Circle - 12.25"
Motor Width - 10.5"
Motor Depth - 5"
Basket Depth - 7.75"
Displacement - 0.24 cu. ft.
Weight - 72 lbs.

T/S Parameters
Electrical Q Value -Qes: 0.46
Mechanical Q Value -Qms: 3.29
Total Speaker Q Value -Qts: 0.404
Free Air Resonance -Fs: 21.00 Hz
Equivalent Compliance -Vas: 74.0 liters
One-Way, Linear Excursion -Xmax: 54 mm
Efficiency -SPL 1W/1m: 83.76 dB SPL
Effective Piston Area -Sd: 480 cm^2
DC Resistance -Re: 4.2 ohm
Nominal Impedance -Znom: Dual 2 ohm
Thermal Power Handling -Pe: 2000 W
Force Factor -Bl: 18.16

 

i pump about 14 gallons every fill up same sunoco same 93, use to calculate but i gave up on that. I run around 180-190 on the 14 gallons so im basically gettig around 12-14 mpg depending if my foots heavy, but i am sporting 19" lowenharts and coilovers. The wheels reduced my mpg by a little but i gave up counting i believe it is the city like how everyone stated, but then the 400 and the 300 runs around the same mpg hmmmmmm anyonne lookin to trade a 400/430?

 

180-190 on 14 gallons I'm getting about 265-290 (depending on freeway driving) on 14 gallons of 91 in my 400. I just got a fault for running rich so my new MAF should be in from Lexus on Tuesday. I was getting about 330 before.

My car is on heavy *** 19" ssr viennas too, running on tein ha's dumped.

In pure city driving I get between 16-21 depending on how much I crank the air conditioning.

 

I disagree with "Keeping it under 2k RPMs most of the time". I've found this is actually worse for gas mileage than hitting the pedal a little harder.

I don't warm up my car at all. I crank, back up, and go. As soon as it says 'Check Completed' I'm out. When I'm accelerating normally, I put the pedal about halfway down, get up to my speed, and then maintain. Getting to your desired speed quickly, and within reason (not flooring it) is better than a gradual climb to that speed.

It's also better for your engine as well, since higher RPMs will make the engine operate under load and burn all of that crap out. If I've been in heavy traffic or idling for a while, I make it a point to floor it on the way home to burn out all the build-up that occurs during idle. Idle is the worst position your car could be in when you can help it.

I have an IS250, and using 91 octane I get 27.5 MPG that's both city and freeway, SoCal traffic and no traffic. 30-31MPG on open freeway and 21 or so in bad conditions.

I know a V8 GS is different, but I get better than sticker on all my cars I've had because I do those things I mentioned above. I never use fuel cleaners, no aftermarket anything, and I change the oil every 5k like the manual says.

 

Just do a full lexus service tune up. They will flush out everything. new filter, oil, tranny fluid and etc.... That's what everyone basically asking you to do. Problem with that is... Lexus will charge you an arm and a leg. lol

Do it once in awhile from the lexus service center is good. Just to show it on record. Plus, they give you free car wash and a full tank of gas.

 

what did u mean u dont warm up? i dont recall anyone saying you need to warm her up. i crank up and go to....i CONSISTENTLY average better gas mileage doin it UNDER 2.2k, went from a average 16 mpg to a average of 18 after cleaning throttle body and MAF and conciously keeping foot off gas.


i knew bout free wash but they FILL your tank? my local place really does suck then. granted i cant recall last time i had ANYTHING done by them in last 4 years before that i used to go to them