Since I got my car about two months ago, I've been really trying to keep track of the gas mileage. I reset the car's computer readout at every fill-up. I have found that if I check the computers' number against the old-fashioned way of dividing the miles driven by the gallons required to fill up, there is quite a descrepancy. The computer usually says around 27 MPG, but when I "calculate" it out myself, its more like 22-23 MPG. I drive about 40% highway and 60% city by the way.

My question is: Which is more accurate, the computer or my old-fashioned calculations? I'm skeptical because I've noticed on a few reviews of the SS/SC, that they come up w/ lower numbers than typically advertised, and I wonder if maybe they calculate the MPG themselves rather than using what the comp. says. I know they are driving it pretty hard, but some are even long range tests. Not that 4 MPG makes that much difference to me, I'm just curious if anyone has noticed this as well or if they know something about the computer's calculation method that I don't.

 

I just calculated mine real quick and there is never more than 0.2 L/100km difference between my computer and old fashioned way of calculating.

So based on my fuel economy, the variation is in the range of 2-3% accuracy, which I think is not that bad.

 

Mine is typically right on the money . I average about 23-25 by dividing the gallons I fill by the miles driven . My DIC typically says 25-26 mpg avaerage . Pretty accurate I think , in my case anyways .

 

I'm hoping that my car just needs to be broken in a little bit more. From the posts so far, it seems my car's DIC is fairly accurate I guess. Just thought tha the numbers would have been closer. I never really trusted the calculation method of dividing gallons into miles driven because I would imagine that not all cars' gas tanks cause the same back pressure for the nozzle, thus varying what exactly is considered "full." Thanks for the responses anyway.

 

As mentioned the mileage calculator for the DIC is rather accurate.

However, remember that this uses all the vehicle data so if you change the height of the tires its going to throw the DIC, speedo and odo off.

 

dam i get at least 31mpg driving like an ass in town..... you guys get **** milage

 

I have found that mine is off and I know others that theres is off as well. Mine is off by 3-4 mpg.

 

MIne is off as well...Last fill up I got 28.8 MPG and the DIC said 31.4 MPG...and it's always been off...

 

well, let me ask you guys this... how is it possible that you know EXACTLY how much gas you are dividing by the miles? o yea... you don't... that's why YOU"RE always off by a few mpg.. the DIC is correct...

 

If you're calculating it yourself, make sure you always fill the tank the same way. Its best to just let it fill and click off when its ready; don't top it off. In fact the "experts" say its best to always fill up at the exact same pump to help insure accuracy (some pump designs may click off sooner, etc.).

I say its easier to use the DIC.

 

also, mileage will go up alot after a few thousand miles... i couldn't get it over 22 when i first got the car... now it's usually around 28 with some spirited driving... if i'm just cruisin on the highway i can keep it around 35-40mpg @ 80mph

 

I drive to school (highway) and work (town). I do about 250 miles a week. I beat the crap out of this car. It sees that 7K redline almost every trip. I still get between 20-22 mpg every tank. To me this is awesome coming out of my Camaro.

 

Personally I figure mine when I fill up then you know exactly how many gallons your car took and divide that by how many miles you have driven.

 

hows your fuel range on your DIC? when i got my 'bolt and filled it up it was around 410 miles before refueling. now mine has really decreased ( 380 to 360 fuel range ) but i still keep my MPG steady- 30~32 mpg. thats both city and interstate ( i take the interstate as offten as i can and i do about 5 over the speed limit-plus i hate lights and slow ppl. at least on the interstate w have 3 to 4 lanes to pass )

 

I check the DIC and calculate my own mpg every time I fill up and the DIC is always 1-2mpg high. I go to the same station and always let the pump click off on its own, so I tend to believe that calculating it by hand is more accurate. Because despite what the DIC says, if you went 300 miles and put in 10 gallons, you got 30mpg in the real world, period. However, it doesn't really make that much of a difference to me. As far as overall mpg goes I only get 25-29mpg depending on how bad traffic has been lately. Anyone who has an SS/SC that claims they get more than 32mpg or so probably just checks the DIC and would get lower, more accurate numbers if they did the calc out by hand. Before calling BS on me for saying this, do the calc and see what you get. I always get the DIC to be 1-2mpg high so I trust the way it calculates and just add in my little correction factor. Or, perhaps they get better gas mileage because they cruise slow at like 60mph constantly for all their driving, because if you are like me and cruise at 80mph your economy goes to ****. PS-For one tank I did try to get max economy by driving 60mph everywhere, staying at low RPMs, coasting with the clutch in, etc. and 30mpg was the best I got. Also, I would be very skeptical of anyone getting into the mid 30's since the SS/SC is rated at 24/29. I know GM underrated the hp but there is no way in hell they would underestimate the economy.

 

just sitting at a fast food driven alone your going to lose a few mpg. better and faster to run in order the food, grab it and your on your way! also you have to make an effort to laugh at everybody still sitting in the drivethru waiting to pull up and order!

 

btw, an oil change will help with the mpg too.

 

that ONLY works if you run the tank till it's completely and totally empty... otherwise, of course it's going to be off because you still have gas left... that's where the few mpg are coming from...

 

I agree w/ you 100% artawesome. I drove an entire tank highway only w/ no stops at about 75-80 mph, and at the end of the trip (I reset the DIC before leaving), the DIC read 33.4 MPG, but when I did my own calculation, I got roughly 30. It doesn't sound like a big difference, but that is roughly a 100 mile range difference. I can't see how some people are getting such high numbers, even if their car has been broken-in. I only have 1800 miles on my car, so maybe after about 6 mos. it will increase.

 

I don't understand what you are saying. If you reset your trip odometer just after filling up, then drive 300 miles, and to fill up your tank at the end of that 300 miles takes 10 gallons, that means it took your engine 10 gallons to go 300 miles. The leftover gas in the tank has nothing to do with it. That extra couple gallons in the tank only means that you could have gone a little further before filling up, but your MPG would be the same, assuming you drove the same way as before.

 

if you reset your mpg on the car it should say the same... do you always reset the meter when you reset the trip meter?

 

Yes, I reset everything every time I fill up--the MPG meter, the trip meter, avg. speed, etc. That is why I'm confused, because everytime the MPG meter is off by about 3-4 MPG from what I hand calculate. Oh well, its good gas mileage regardless.

For the person who was asking about the fuel range calculator, It really shouldn't be the same everytime, because I'm pretty sure it bases your range on your most recent mileage, so unless you drive exactly the same everyday, it should vary from tank to tank. That thing is kind of pointless because it stops giving readings once you go below 40-50 miles, the time when you need it the most.

 

weird...

 

You are wrong and this makes no sense.

On topic, I agree the DIC reads about 2-3 MPG higher than actual.