Mpg/thermostat exsperament

[LiquidOcelot]

Ok little back story first, im a Lexus mechanic who knows what and what not to "neglect" maintenance wise on my cars. My thermostat was stuck open since i got it from my grandma. So it never really got to closed loop. Commute to work is 40 miles round trip and i usually use 1/8th a tank per round trip.

Edmonds rates the car 26 city 30 highway 28 combined mpg

Test subject: 97 Geo Prizm 98,000 miles stuck open thermostat prohibiting closed loop

Test 1: full tank of gas until needle is below E line calculate miles÷tank capacity= mpg

Result 1: drove 302 miles needle well below E line. 302÷13=23mpg (not bad) filled tank 11 gallons almost exactly. (Wait i had 2 gallons left) rounded down to 20mpg per gallon and re calculated. 302÷13=26mpg. (Now we're talkin"

Current test: same vehicle with new thermostat allowing vehicle to enter closed loop


Stay tuned for end results.






I know it should improve mpg since open loop keeps the fuel system pumping more gas than it really needs too. So im curious to see under my normal driving conditions if just replacing the thermostat makes a difference


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[ABROB]

I'm confused by your math.  If you put 11 gallons in to refill it, doesnt that just mean you only burned 11 gallons?

302 ÷ 11 = 27.5? 

[LiquidOcelot]

I'm confused by your math.  If you put 11 gallons in to refill it, doesnt that just mean you only burned 11 gallons?

302 ÷ 11 = 27.5?

yes you are right. math is nit my strong suit lol.

here are the results.

this time i was able to get 355 miles to 12 gallons. that puts me at an awesome 29.5 gallons

and if my math is correct, just changing a faulty thermostat got me 2 extra gallons.

wonder what else i can do to improve fuel economy.

remember kids, as long as you maintain your vehilces they will last you forever, unless its germen, then 70k tops lol

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[YardBurner]

Outstanding. But that would be 2"MPG".

Wish I could get 20.  2008 Suburban.  20 plus on the hwy but 15-18 around town.
Would love to switch to a smaller more fuel efficient car but I need the size.

We have a 2006 Scion XB that was our son's and I've been using it a lot more for
when we don't need the big beast.

30 MPG doesn't hurt a bit!!!!

[LiquidOcelot]

Outstanding. But that would be 2"MPG".

Wish I could get 20.  2008 Suburban.  20 plus on the hwy but 15-18 around town.
Would love to switch to a smaller more fuel efficient car but I need the size.

We have a 2006 Scion XB that was our son's and I've been using it a lot more for
when we don't need the big beast.

30 MPG doesn't hurt a bit!!!!

lol my highlander gets 19. my old accord got 17, my last civic got 22 and my old 240sx got 24. all 4 bangers but the geo is for sure my the lightest of the bunch.

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