Short distances and then add in some stop and go traffic (lights) and the lpg/mpg will drop. Best mileage is highway in 5th gear. If it is a manual - the sooner you can get into 5th gear the better the gas mileage will be. In an automatic - much harder to tweak driving to maximize the gas mileage.

How hilly is Toronto? That will also be a factor. Cold weather will also make a difference and get worse mileage. to me it would make sense to open the car up to 3500-4500 rpm a couple times a week. With a manual the damage to mileage can be greatly mitigated. Using 89 octane and some hills could mean that you need to get into the gas more for the hills as you will not have the same power output as when you run premium.

 

The commute is pretty flat and straight, no major hills.

I have an auto tranny and it does seem like tweaking it would be difficult.

I should probably start using 91, but i recently read a threat where a member logged his commute using excel over a few months and didn't notice any significant difference in mpg, so i basically started using 89 because of that thread.

Could it be that my car needs a tune of some sort?

 

Seems a bit high unless you spend most of the time sitting in traffic. Is the maintenance kept up on it? Many factors can cause higher fuel consumption, even a vacuum leak since it would be adding more fuel into the mixture to compensate for the extra air.

 

I've performed most maintenance that individuals on the forums have recommended except the CCV. I do have this weird quirk where the engine sort of shudders (i can feel the engine being put under load in park) when i turn on the heated seats or put the window down. Not sure if this is a symptom but i find it kind of strange.

I have all the parts for the CCV but just waiting for a good time to install it. I think you are correct in that it might be a vacuum leak, it might be too small to detect by a smoke test cause i couldn't see anything the last time i did one.

 

CCV change would not hurt, all filters changed, and new plugs as well. 89 octane should not cause a ton of difference especially on flat terrain. Anyway to change the drive so there are less stop lights (even if it adds a couple miles)? Adding a couple more miles is not a bad thing especially with winter coming (and maybe there up 'nort) - you want to get the car to full temp for a good bit of driving to boil off water in the oil and catalytic converter/muffler.

Without hills - that is the mileage killer, starting and stopping.

 

I'll give it a shot and will see if it makes a difference. The short runs could be the problem.

I changed the plugs about 3 years ago and car seems to run fine (no misfires, no engine hesitations on start up or acceleration). Would you recommend changing them again?

 

Do not loose a lot of sleep here until you do your homework.

All fuel economy values are "relative" and there are a LOT of variables that feed into total fuel economy. Most people over state the fuel economy value they get. Kind of like sex and snowfall, almost everyone lies about it!

"City" fuel economy is also RELATIVE. City driving to one person is VERY different than "City" driving to another person.

So lets take the OP's info. Translating to values I understand, jarjar is getting 15 MPG in the city and has a daily commute of about 7.5 miles. This may be "typical" depending on the driving conditions.

The first thing the OP needs to do is RESET the OBC each time the fuel tank is filled up and track BOTH MPG/L100k AND MPH/kph. The AVERAGE MPH/kph is CRITICAL to understanding how the vehicle is being driven. Additionally total distance for each trip is also critical because 7.5 miles and the engine is not likely fully warmed up and the engine oil is not likely up to temperature depending on the start temperature of the engine oil.

One thing everyone FAILS to understand is a vehicle will get EXACTLY 0 MPH/L100k while the vehicle is not moving at a stop light, stop sign or in stop and go traffic. A 0 MPG/L100k will KILL any decent possibility to obtain good fuel economy. Averaging 0 into any other number will KILL the high number!

The main thing that impact decent fuel economy is the vehicle not moving and the engine not getting up to temperature either due to a short trip and/or a soft thermostat.

You also need at least 3 tanks of fuel to average the fuel economy IMHO due to temperature and driving condition variables.

So report back the AVERAGE MPH/kph for the next figures for each tank of fuel. Might be worth noting the engine*******t air temperatures before the start of each trip as well. Temperatures can be a VERY useful pieces of data. If you know how to monitor the engine coolant temperature or better yet Log it with an OBDII App this can also offer a lot of good data.

15 MPG for short trips in Toronto Canada where the evening temperature are near or below freezing this time of year and if the fuel is Winter blend fuel, I would not be getting worried other than to track the the engine coolant temperature is actually getting up to 96C and then also monitoring the underside of the oil fill cap for Mayo and "Managing" the mayo as needed by addressing a soft thermostat, drivig the car for longer distances to fully warm up the oil and if needed removing the oil fill cap overnight to allow the water vapor to exit the crankcase.

 

I get around 16mpg with lots of cold start traffic driving on 91. Sounds normal

 

I'll definitely log my rides and check the temps. I was thinking it would be a bit better. lol.