What is your city vs. hwy mileage ?
 

A while back, MetroMPG and some others here were surprised to see that their around town mileage was much higher than their highway mileage.

A car such as MetroMPGs' could get around 60 + MPG ( US ) on the highway, but easily over 80 + ( and over 100 at times ) in the city.

I have a SuperMID trip computer in my car which is a 1993 Honda Civic DX with an automatic. I don't have cruise control. My tires are aired up to max sidewall pressure ( 44 PSI ) I also have a grille block and 1/3 belly pan installed which helps warm up times ( and aero at highway speeds )

My drive to work consists of 5 lights - 3 of which I know the timing. There is a hill that I coast in neutral for 2/3 of a mile. I only coast when there is no car behind me for a good half mile or so.( so not very often ! ) The speed limit is 45 and 50 MPH at the top of the hill.
I find that switching the car off for the one minute or so of a light does not seem to really help much ( my trip average registers less than one MPG difference ) , and I feel uncomfortable doing that, so I don't use that trick.


Despite doing my all out best, the best that I could do on the 7 mile stretch of road that I take to work, is less than 40 MPG.

Much to my surprise, 50 degree weather will drop my trip average to as low as 28-29 MPG. 68 degree weather results in 38 MPG ( What a difference a few degrees makes ! )


On the highway at around 60 MPH, I get around 48 MPG- to a high of around 50 ish.

Since the SureMID trip computer shows your instant MPG reading ( actually Km/ L which I convert to MPG) I noticed that my instant reading is around 18 MPG when I first start my trip ( cold engine ). As the engine warms up and I get to around 45 MPH, my instant readout goes up to 85 - 90 MPG.

( To those not familiar with an instant readout like a SuperMID has, the figure is constantly changing. The slightest pressure on the accelerator will drop the figure from 90 + MPG to 30. Lift up on the gas, and you are instantly getting over 100 MPG - till the car slows and you have to press the gas again )

I had assumed that when the comments were made about the super high mileage figures, that everyone was talking about their instant MPG readings and not the trip average.
Much to my surprise, this was not the case.

So, I'd like to ask everyone that has a trip computer about what kind of mileage that you get in city driving ( not rush hour - just rural roads )
In your response, please tell how much is coasting / engine off ... etc.
What is your figure without the engine off ?

Also, I'd love to see what you guys that have an automatic are getting.


One more thing that I found by using the SuperMID, is that a light that last around one minute cost me almost 2 MPG on my trip average.

These statements seem contradictory. Would you please clarify?

Cd,
The vehicle is a GM 4 door sedan with the standard (at the time) 3.8 V6 with the 4L60E trans and weights about 1600 kgs (3300 lbs approx)
No mods and factory a/c which gets used quite a bit especially now (Summer here) with temps around the 40 C mark (105 F) and a dark blue car with a dark grey interior.

City MPG sucks at around 11 ltrs / 100 kms ( 21.3 US mpg)
Highway is better at around 7.0 / 100 kms. ( 33.6 US mpg)
These are for unleaded 89 octane.
Running on LPG the figures are about 15% more fuel used.

Normal hwy speeds are 90 / km hr (55 Mph)

Cheers , Pete.

I never exceed 45mph on my drive to work, about 3.3 miles. 3 stop signs, 7 lights. Half the distance the speed limit is 25mph, but I coast better at 30mph so I speed a little. On average when I do my best to avoid the red lights, coast as much as possible, I can get 22mpg, over 350 miles/tank. As the wife uses the car as well, has a 1 mile trip, between the two of us winter mpg suffers to 19.5mpg over 1000mi average.


Highway mileage is far different. The lowest I've gotten was 28.4mpg, cruising at 85mph over rolling hills and climbing mountain passes. The best I've gotten was 35mpg, using all the tricks, pulsing up, coasting down, holding the rpms for best torque vs. load, never exceeding 75mph with the accelerator, only by coasting (got 104mph coasting with 5 people down one pass!!). I've gotten that unloaded (just me) and loaded (5 people, full trunk). Both of those are over the same route I can get 28mpg. Driving style makes a huge difference for me.

I'd like to get better intown mpg but stock my car and route don't allow it. I do ride my bike when weather is decent. I hate biking at temps below 25-30*F. Just too cold for this rusty Alaskan. :P

All this figures are an unmodified car, completely stock. Grill block would help, warms the car faster, but the 'stat is sticking, and pushing temps above 220* before it pops open, so I can't risk overheating till I get a chance to change the 'stat. Suck though, since when it opens the freezing radiator rushes in and temps plummet to around 170* and climb very slowly to 185*. I need a garage, some real antifreeze (not dexcool) and a tranny flush. The car needs work badly, and I haven't the time or money right now. :(



Edit: Neat! Peter you have a similar setup to me, cept I've the 3.1 and the non-heavy duty transmission.

This is not what I see with the Insight at all. Though I've never done any long-term measurement (because I just don't do that much city driving), on a fairly smooth highway I'll see anywhere from 65-75 (freeway) to 100+ (rural road at 50-55 mph). In the city? Maybe 40-50 average, if you leave out the slightly downhill stretch through Carson City. I often fill up on the north end of town, and if I catch all the lights will be at 120 mpg or more before I get to the south end, and have to start climbing the hill.

I dont have a metering device but do fairly accurate log keeping, filling with only 2-3gallons from empty and using the low fuel light.

It really depends on the terrain, AND the skill of the driver to glide with the engine off.

I'm improving all the time regarding engine off glides, this area is the secret I think.

My highway is better too as I'm using drafting much more effectively, without sitting right up someones ass for long periods of time. Quite often I'll slow down to let a bunch of cars or a truck catch up, and then join them in formation for awhile, dropping off after a bit and then looking for a new victim, whoops I mean group of vehicles.

Because my driving is a mixture of short freeway 95km/hr, rural 70-80km/hr and urban 55km/hr I can't really differentiate. My home city is very hilly, so sometimes the motor is off for huge periods of time.



However one things for sure. My ability as a driver to hypermile makes all the difference.

And these skills vary depending on the terrain, speed limits and level of congestion.

I'm getting better at pulling into parking places at 1 or 2mph with the engine off for the last minute or two. Sometimes I'm parked a bit funny. I went from 4.4l/100km to 3.4l/100km when I really concentrated on engine off and cruising with the bunch.

I always get worse mileage around town with my cars. Unless I can get it into OD, the mpg is not too good. When I know a light is going to be long, Ill shut the car off, that helps. Or at the very least, Ill shift to N, the mpg goes down about half as fast that way. Same as if Im at a stop sign and theres traffic for as far as I can see (typical on the way to work) Ill just shut it off till a clearing gets close.

Now my 92 Trans Sport van is another story. I can usually get better mileage around town than on the highway. And especially when towing, which I do a lot of with the van. I dont keep a fuel log because it is mainly used for odd short trips and for towing.

Yes - I noticed the same thing.
Switching the car back on once warmed up shouldn't take barely any fuel at all.

I need to redo the tests.

I shouldn't post based on memory alone.


( I should point out that I am usually stopped by only one light that lasts less than a minute. If I had a longer trip and more lights, this would be a more accurate test of shutting off the engine at stoplights. )

Thanks for posting folks !
I'm guessing that most of you have automatics.

Jamesqf - how much of your high mileage trips are done coasting with the engine off ?

I find that I can coast with my automatic ( engine on ) pretty well, but when I shift back into Drive while moving, the car shudders and suddenly slows at anything under 50 MPH. ( almost as if I have stepped on the brakes )
This is very unsafe, so I can't do it with traffic behind me.
With a manual, I'm guessing that you do not have this problem.

To clarify: my sub/urban mileage is only better than my highway mileage when using lots of engine off coasting and pulse & glide.

And I don't P&G on the highway any more. Just driving with load.

It's hard to say, because I only rarely coast with engine off. The Insight has the mode where the fuel is cut off, and the hybrid system is recharging the battery. The occasions I do shut the engine off are mostly in the winter, when the system otherwise keeps fuel flowing to try to keep the engine temp up.

I don't think those would be my best trips, anyway, at least if I figured round-trip, since I'm climbing a mountain on one half, coasting on the other, and lose a little bit more FE uphill than I get back on the downhill. I'd guess that I average right around 70 mpg fot the up/down mountain parts. The best are level or almost so, where the Insight's lean burn can kick in.

Cd: engaging drive from neutral when moving in an auto requires you to rev the engine up then move the shift to drive while the motor is still spinning, immediately after you have removed your foot of the gas.

Much like a 'double the clutch' technique.

Dont know if you guys use that phrase.

I get horrible city MPG, I think its mainly due to my city and my cars weight.

I weighed it in at 4000lbs with nobody in it but me. Going uphill to a stoplight every 300 feet really hurts city as a result. I get as low as 12 mpg sometimes on short trips through town. With some work I can get it into low 20s but most of my city trips arent short enough to get it up there. The car is barely up to temperature by the time I'm at the destination. Even with full grill block.

On the highway I've gotten as high as 35 MPG but I've averaged probably 32~ in summer and 28~ in winter under normal cruising. Automatic transmission

Thank you !

I'll try that the next time that I drive. I really appreciate the tip, since this may change my driving style completely ( more coasting ).
I have always noticed that the engine revs up when I get that stutter before shifting back.
In my mind I thought that revving the engine manually before shifting back might have damaged the engine / transmission .

Geez ... how foolish of me, since I have probably been doing more damage by not revving the engine.


I notice that above 50 MPH or so, the car does not shudder and slow, and at around 60 MPH, the change back to 'drive' is completely seamless.The engine also does not rev by itself.

Thanks again for the tip.

If this is already a 'sticky', I missed it.


Hey folks, thanks for posting your mileage figures, but can we all mention whether we drive a manual or an automatic ?
Thanks !

My Vibe is automatic.

I get about 35mpg in city driving @ 40mph. My city trips are never that long, which means the car does not warm up until im on the hwy. However in the city I do as much EOC as possible and I accelerate quickly to get to cruising speed.

My Hwy mileage is a consistent 40-42mpg, achieved @ 55mph with the cruise control engaged. I have seen that P&G on the hwy gets me up to the high 30's quickly, but then plateau's until I set the cruise control.

The car's original est were 22/25 I believe.

What is your
 

Let me say something before I respond.It requires a minimum of 22-miles of continuous driving at 50-mph to warm a car up.The short commutes many of you members are reporting on are all for"cold" cars and all your mileage would be higher under fully warmed conditions.I suffer from the same situation,as my commute to Denton is only 6-miles,so the T-100 is never "warm" either,except for "out-of-town" travel.------------------- All that mentioned,the truck does low 20s if forced into extended urban driving.Mixed-commuting with tools and building materials on board is in the 26-mpg range.The truck does around 36.5 mpg at 55-mph.It does 32-mpg at 70-mph,falls off to 31 above 75-mph.At a constant 45-mph it gets 39-mpg and if the City of Denton would syncronize the traffic lights,would get above 40 mpg in town.Is that muddy enough water for you?

not true. If I rev-match my GP it'll downshift and start accelerating. GM decouples the engine ob coasting situations, even at highway speeds. While coasting at 80mph down a pass my engine is at about 1600rpm. If I put it in N it drops to 1200rpm, sometimes 900rpm. There is nearly no engine braking ability with my transmission.

There's one pass I enjoy rockin' down, and I've found N vs D results in 5mph difference of speed, ie 97mph vs 102mph coasting, 97mph being in Drive.

Aero, my temperature guage goes up to 'normal' level within a few minutes ( like around three minutes or less on a 65 degree day. )

So this measurement is for the temperature of the coolant and not the engine or ..... ?

I'm confused.

normal
 

Cd,the engine coolant may,and probably will make it to operating temp within a few minutes.The snag is that all the lubricants and fluids,as well as the rubber components of the car will not and can not achieve their equilibrium temperature until the car has gone 22-miles under constant driving.And for every "cold-start" we begin the process over and over,loosing all advantage of a "warmed-up" car.Throw stop and go driving into the mix and it's a double-pronged assault on your gas tank.--------- This is why urban mpg is typically lower than highway mpg,although it should be the other way around.

Not necessarily so. Even in the winter, the Insight only takes about 10 miles (on level roads) to warm up to its normal operating temperature. Since it takes me longer than that to get into town, most of my city driving is with a warm engine.

Warm up times vary according to ambient temps, speed, incline, load, vehicle type, coolant condition and ratio of water to glycol, driving technique......

I duct 100% intake air from the top of the exhaust manifold, reducing this ratio when climbing mountains in the height of summer. At the top of the mountain I pop the bonnet and change back to fully heated air.

Thanks almightybmw! regarding rev-matching.... I have only driven older auto trannys, mostly pre 95' Toyota diesels. Newer technology auto's must have varying performance characteristics.

Cd: maybe you should seek corroboration for your model of vehicle, and determine the level of engine braking (a rev counter showing high engine speeds with no throttle while moving means neutral will save gas), will guage what could be gained, by using neutral while moving.

That said, I usually flicked to neutral in my previous autos, but only when a neutral glide would be sustained for a reasonable amount of time and distance, which can occur descending even a minor incline.

22-miles
 

jamesqf,the numbers I used are from SAE investigations by General Motors Research Labs.Their findings are,that for any car,at any given ambient condition,that car will not reach it's peak equilibrium temperature and peak efficiency for all fluids and lubes, until it has been driven continuously for 22-miles at 50 mph.Anything less yields higher viscosities , higher road loads,and higher fuel consumption.

Its about 12 miles into town, so my car is somewhat warmed up by the time I get there, but on my city driving segments I’ve been able to average low 50’s (winter), high 50’s (summer) through the use of as much ICE-off time as I can manage.

On the highway its mid 70’s (summer), high 60’s (winter) at normal highway speeds, DWL when traffic density allows, and ICE-off on every coast-able downhill. Subtact 2 to 3 mpg for driving with the lights on. I don’t draft because it offers little to no MPG benefit for my car.

Wow! That's way more than I'd have guessed. How do/did you determine?

For highway MPGs I recently gathered some data and posted it here:

http://ecomodder.com/forum/showthrea...ting-6947.html

As for city mileage, when you say city I think of a fair amount of stop signs and red lights, my car is in the low 20's in these conditions, although of course it can and will vary greatly. My car is an automatic.

Might be a good average, but I'd be really surprised if the mostly aluminium 1000 cc engine in my Insight took the same time to warm up as a typical big-block GM V8.

The engine warm-up isn't the only issue, though. The temp of the transmission fluid, tires, bearings all affect efficiency, and warm up much slower than the engine coolant.

I've seen this during testing. Repeated runs over the same stretch of road on cruise control, the segment MPG readings continue to climb for a surprising length time after the coolant temp stablizes (indicating the other components are still getting up to temp).

Haven't measured it for my car. I'd be a little surprised if it were as much as 22 mi., but it's certainly well past coolant max temp distances.

Yep

I had a Citroen BX19 16v that was fitted with an oil temp and water temp gauge.

On the highway at about 13 degrees C, the oil temp took around 3 or 4 times longer to stabilize than coolant.

I would guess with that car about 10miles

I can watch trans temp on the SGII in my Escort, and it definitely does take longer to reach operating temp than the coolant, and the lag varies depending on driving conditions.

No idea exactly how it relates to a car or light truck, but I use to operate 3 axle 19 ton curb weight trucks designed for seismic surveys for the oil industry. They were equipped with transmission oil temperature gauges (Alison 5 speed automatics). When moving from job site to job site we drove them on the highway (anywhere from 50 - 15000 miles). In cool/cold weather, it would usually take anywhere from 50 - 100 miles for transmission temperature to stabilize at a peak reading.

Sure - but I bet those transmissions weighed about as much as the whole Insight does :-) And were mostly iron & steel. Aluminium has 4-5 times the thermal conductivity.

By driving the same scheduled route with or without my lights on under the same temps and wind situation, something that happens regularly when the day length is rapidly changing near the equinoxes. When you are running at the minimal energy budget needed to achieve 70mpg, the power hit needed to run the lights takes a bigger chunk out of that energy budget than it does when you running at an energy splurging 20mpg. On my F150 I can hardly notice a difference between lights on and lights off.

Yet another reason to think of FE in terms of fuel unit / distance instead of distance / fuel unit (mpg).
An additional 0.42 - 0.64 gallons consumed per 1000 miles due to lights on.

When you're getting the kind of high FE that Bassjoos does, little things like lights do make a bigger cut in FE. I notice zero difference in FE with lights on or off as well. But I do notice with the 6000 wagon, climbing this one hill on the way home from work loses me 1-1.5 mpg. The same hill with the Celeb loses me 2-2.5 mpg.

It's the only vehicle I've ever operated that had a transmission temperature gauge.
Yeah, it's about like comparing grapes to watermelons. ;)
No matter.

Itty-bitty car vs 20 ton 6x6 truck with Allison MT553 5sp AT (and DT466 in-line 6 diesel )

• Greater thermal conductivity >> greater heat dissipation during warm up
  >> longer warm up for oil in itty-bitty car transmission.
• Itty-bitty transmission mass vs MT553's mass (900lbs-1100lbs ?????)
  >> shorter warm up for oil in itty-bitty trany.
• Less work moving 1,500-3,500lb curb weight vs ~40,000lbs curb weight >> a whole lot less friction
  >> longer warm up for oil in itty-bitty trany.
• Tiny or non-existent transmission cooler vs large transmission cooler
  >> shorter warm up for oil in itty-bitty trany.