Soo I've noticed that my car isn't nearlyyy getting as much MPG as it use to but I wasn't sure if it was bcuz I drive more in the city now or what. But today on my way to the shop I really paid attention & reset my homelink screen thing to help me keep track & yup it proved that I'm most def losing MPG. The trip from Wentzville to Troy or vice versa, I use to get like a average of 30-32 mpg on cruise control but today I was only getting 19-21 which reallyyyy upset me. I have noooo idea what's going on but I gotta fix it with gas prices going up. Premium is flexing between 3 bucks a gallon to 3.30 a gallon so yeah I literally can't afford to lose this much gas mileage since I will be working at the shop for now on. So I'm wondering what could be causing this. I'm 100 miles away from her having 48,000 miles so idk but it's annoying. Any help would be appreciated, my dad says it's my right foot that's the problem lol but that doesn't make any sense if I am on cruise control. Thanks guys!

 

What was the last mod upgrade you made to your engine? Btw, have you check your tire's air pressure lately?

 

Could be the winter gasoline. All cars will get worse mileage in the winter due to how they make it.

 

Thats about what I average now. Something isnt right if thats what your getting.

 

i want to ask is when did you do the tune up and oil and change the air filter for your monte. also i would check the air pressure i know the air in the tires do alot of mpg loss do to not enough air in it. i just want to ask because it does not seem right at all i know the super chargered 3800 like you have gets what you were getting. now it seems like it is droping like there is not getting some thing or some thing simple may be causing it.

 

I haven't done any engine upgrades. I checked my tire pressure & reset them a couple weeks ago. It's only been around 2,000 miles since my oil change. I haven't checked my air filter in a while. I plan on checking it once I change my coolant this week. Idk if that has anything to do with it but my coolant system is like destroyed. My coolant looks like a chunky, orange/brown shake. But it's been like that for while so why now?

 

Are you just checking via the car computer or are you manually calculating your gas mileage when you fill up? For some reason the computer on my 03 is totally off and I don't rely on what the computer says. The 05's computer is almost dead on. I still calculate manually on both cars on every fill up.

 

I will echo some of what's been said.
1) Winter Gas = Less MPG in St. Louis Area.
2) Don't trust the car's figures, I do mine in a spreadsheet every time I fill up and the car has never calculated it right. Miles driven since last fill up divided by gallons purchased is the only way to get MPG. I have an average MPG since I bought mine over 20k miles ago of 23.69, but last three tanks have yeilded my 19.6, 18.3 and 18.36 MPG, but I also use my remote start every morning, so I know some if it is my fault.

Side question: Are you going to put dexcool back in or go with the traditional green coolant?

 

I use the computer thing now. I use to calculate it myself but I keep forgetting. My computer use to be right on so I thought it was dependable. & I will most def be putting regular green back in it. I never put dexcool in it in the first place. I dont think we have changed it since we got her. The dexcool has f'ed up my coolant so noo way I'm doing that again. Thank goodness my dad has a pressurize coolant exchange machine or else i prob couldn't get all of the junk out

 

a few causes why i get less gas miliage,

Snow! spinning tires, stop and go,= less mpg
(durring the "Blizzard" we had in MN i decided to be out n about in my saty that usually gets 30+mpg got 18mpg)

Winter gas, if i'm not mystaken it contains less ethanol
Tire pressure fluctuation, becuase of the warming and cooling tire pressure fluctuates a bit becuase oxygen moliquels are smaller when cold hence y aluminum rims are more prone to leak when it's winter

Starting your car to warm up,
since winter has hit my car only gets about 5min warm up time but multiply that by 2-3 times a day

all in all adds up! i miss 30mpg like it was in summer

o i forgot YOUR RIGHT FOOT,
i catch myself getting on it alittle more in winter, the cold air gives it some more pep!