I kept a detailed log of my fill-ups, cost, gallons, and mileage.

Start: 0 miles, full tank of 20 gallons.

15 fill-ups* later: Mileage 3,616 Gallons expended: 149.7
Total cost: $310.48

Total mpg: 24.15

Overall I am very impressed with this. The majority of this driving is higher speed backroad, highway and some town driving. I consider myself mostly conservative, only occasional rapid acceleration and acts of mild stupidity. Car was in "norm" mode the entire summer... no need for pwr.


* (Fill ups do not mean filling all the way from empty)
Stats: 1992 SC400. Mileage: 7X,XXX. Tune up at 60,000 with timing belt, spark plugs and others. Mobil 1 synthetic w/ toyota 8015 8000? oil filter (discontinued) New air filter every 6K miles, synpower FI cleaner every oil change.

 

I find it very odd that so many v8's are getting better mileage than I am.

 

It was determined a long time ago that the SC400 does get better mpg than the SC300 by the fact of the matter: The SC400 accelerates to the operator's desired speed much easier. You would need to rev an SC300 higher in order to accelerate liesurely to 40, 50 60 and beyond. The SC300 according to toyota is capable of getting 1 or 2 mpg more, but i would attribute that to the SC300 driving very conservatively, and the SC400 driving rather lead-footed.

The SC400 can burn ALOT of gas if you accelerate it 0-100 full throttle repeatedly.

 

Yup. You 400 guys are getting excellent mileage.

My 300 5-speed gets 15mpg (mostly highway!) and I'm STILL trying to figure out why.

Still running some tests as I type. The next fill up will clue me in some.

 

yep the mileage question pops up every now and then...i started a thread a while ago about mileage...let me see if i can find it.... https://www.clublexus.com/forums/sho...s&pagenumber=1

there you go.

CEO

 

And I don't have a lead foot. I speed up to about 5 over limit and then let go of the gas till the car goes around 2 under limit, then repeat

 

Wow... that could be a major problem... getting 5 mpg less than a larger, more powerful engine is a shocking coincidence, but TEN MPG LESS.... thats a statistical anomaly, especially if you have a 5pd, which is supposedly superior (in fuel economy)

 

Yea man, thats no good, I get about 22 mpg (95% city + alot of A/C) with my 5-speed. Check your plugs, distributor cap, O2 sensors, etc. Good luck

 

Yep, I know it. I have issues.

I just filled up and calculated 16.1 mpg this time. I put the stock intake back on for this tank to see if the Injen was killing my mileage. Apparently that wasn't hurting me much if at all. (mid 15's mpg)

The car has a recent tune up of plugs, wires, cap, rotor, tranny rebuild, diff fluid, and running synthetic.

I'm quite lost. The tail pipes are CLEAN. Not a spot of carbon so it's not running that rich if at all.

I am running 19" wheels with 275 rubber in the rear. Can't see how that would kill mileage so much.



No check engine light (except at start-up as normal). Could the 02 sensors be bad and not throw any codes plus perfectly clean tail pipes?

 

Maybe, JUST maybe, the larger diameter rims/tires affects your speedometer so much that the mileage you are recording is vrey inaccurate, and you are actually getting better MPG than you think. What size tires are your rears? (Im guessing 275/35/19, which would mean the speedo is 5.6% too slow)

 

Rears are 275/30...

 

Aight, nevermind, your speedo is only 1.3% off, so thats not it. I dont know man, good luck with it though

 

LOL thanks. I'll keep workin on it and we'll see what happens.

</thread jack>

 

Hey CleanSC...sure you don't have a hole in your gas tank?

 

I get 18 regularly in my '92 400. I drive pretty hard though.