Why is my car so bad at coasting

[user removed]

Best way to remember to unplug your block heater is to put your ignition key on the plug or attach it to the cord for the block heater so you have to get the key off the plug you need to unplug. Of course this is assuming you have your car parked in a garage and it is safe to leave the key there.

regards
Mech

[redpoint5]

Originally Posted by jayliu1984

I have a short youtube clip showing how "hard" it is to turn my front wheel.

...However, I still can't stop thinking how much money I would have saved if I have gotten a different car. I had no idea this accord uses this much fuel. The EPA rating is 21MPG city, and I am only getting 18.6, while being laughed at by my coworkers the way I drive (too granny).

...If I can be SURE that this car is all good and this IS how much gas Honda Accord drinks, it helps me to make decision if I want to sell the car when the lease is up or keep it. There is nothing I would complaint about the car except the fuel comsuption.

Your video doesn't show anything that looks abnormal about the effort required to spin a single wheel.

You are already saving a ton of money by having only a 6 km commute. How much money do you really believe can be saved? I'll do a little math below in units I am most familiar with.

Your commute is 4 miles one way, or 8 miles round trip. Assuming a 5 day work week, you might commute 235 days per year.

8 miles * 235 days = 1880 miles
1880 miles / 18.6 mpg (your mpg) = 101 gal
1880 miles / 21 mpg (EPA mpg) = 90 gal

Assuming $5/gal for petrol, the annual difference is $55 USD, or $0.23 cents per day. You are spending way more money than this just by choosing to lease instead of purchasing a used vehicle from a private seller.

Have you driven this route in other cars before while comparing your mpg with the EPA for that car? You will find that all of them perform below EPA because the distance traveled isn't enough to warm up and run efficiently.

If you want to save money, then ride a bicycle instead. Or purchase a good used vehicle from a private seller. Or install a grill block on your existing vehicle.

Why not jack the other side of your car off the ground and try spinning that wheel? I bet it takes just as much effort to turn. This would mean the brakes and wheel bearings are likely just fine.

[jayliu1984]

WOW, so many helpful replies. Thanks a ton.

For accelerating, what does it mean by as fast as possible? The engine revs up to 3k on 1st gear so fast, do I let off the pedal so it will shift? Or do I keep the position and let the car shift itself?

I have seem a lot of people here mentioning about accelerating at a brisk pace. What's brisk? And do all cars save fuel by accelerating at brisk level?

Since I drive city 100% I noticed that I either run at 57km/h (50 is the limit) in 4th gear at 2000rpm, or accelerate all the way to 64km/h so the car will shift into overdrive and keep 60km/h at 1500rpm.

So is this 1500rpm is what you guys want to get to by brisk acceleration?

It sucks that speed limit here is 50kmh whereas most other Canadian cities are 60 so I rearly can archive even 55 before I have to slow down for next red light or traffic.

[redpoint5]

Originally Posted by jayliu1984

For accelerating, what does it mean by as fast as possible? The engine revs up to 3k on 1st gear so fast, do I let off the pedal so it will shift? Or do I keep the position and let the car shift itself?

I have seem a lot of people here mentioning about accelerating at a brisk pace. What's brisk? And do all cars save fuel by accelerating at brisk level?

So is this 1500rpm is what you guys want to get to by brisk acceleration?

...I rearly can archive even 55 before I have to slow down for next red light or traffic.

Somewhere around 80% throttle will give you the most efficient acceleration. I often ease up on the throttle to get the car to shift to a higher gear, but I'm not sure that helps anything. Of course, if you are accelerating quickly only to have to slow down shortly thereafter, then slow acceleration is probably better. Ideally, you will accelerate briskly up to speed, and then coast in neutral to the next stop.

All gasoline powered cars will benefit from brisk acceleration due to lower pumping losses and placing the engine at optimal RPM. Research BSFC for a better understanding of the subject.

Cruising at 1500 RPM instead of 2000 RPM makes a huge difference in fuel consumption. It's too bad you aren't able to travel fast enough to get into the sweet spot of your transmission.

[PaleMelanesian]

Don't worry too much about 1st gear. It's going to be bad no matter what you do. After that, work on the moderate acceleration thing. I'd say aim to keep it below 2500 rpm. I agree about letting up on the pedal slightly at key points to encourage an upshift. After that you can lean on it a little more in a higher gear.

[jayliu1984]

Originally Posted by redpoint5

Somewhere around 80% throttle will give you the most efficient acceleration.

80%

Like almost steping onto it? Wouldn't the engine just inject more fuel making it run rich? It sound so counter intuitive. 80% would make me run like rabit at red light. Or is this 80% something else which is not linearly related to throttle position?

Since my commute is so short, is it benefitial to do that if the car is open loop?

[MetroMPG]

80% would make me run like rabit at red light.

Right. Accelerating at high load is a bigger waste of fuel if the very next thing you do is press the brake pedal. However if the next thing you do after accelerating is cruise in top gear for a long time, or coast a long distance in neutral to your next turn/stop, then it's worthwhile.

Have to keep these things in context.

[jayliu1984]

Originally Posted by MetroMPG

Right. Accelerating at high load is a bigger waste of fuel if the very next thing you do is press the brake pedal. However if the next thing you do after accelerating is cruise in top gear for a long time, or coast a long distance in neutral to your next turn/stop, then it's worthwhile.

Have to keep these things in context.

I have just read couple more ariticles on BSFC and my head has a hole in it resulting from my mind being blown.

Are you telling me that, if I have a gauge that instantly reports MPG, the reading will be higher for faster acceleration. So the more I step onto it the MPG will raise until passing 80% load roughly and MPG will drop again???

This is so counter intuitive when cars like CIVIC has a guage which goes from green to RED when you accelerated harder and harder.

[MetroMPG]

No, the gauge will show what you expect it would: very high fuel consumption when accelerating at high load.

The difference is: the engine is producing the most power per unit of fuel burned when you're in the BSFC sweet spot. In other words: the engine is working at its most efficient. So if you need power, you sometimes aim for that spot (depending on what comes next - see my previous post).

Of course the technique doesn't work as well with a conventional automatic transmission because you have torque converter losses, and you can't control RPM (and therefore load) as well as you can with a manual.

Low RPM/high load acceleration is half the reason why the "Pulse and Glide" technique returns astronomical fuel economy numbers with a manual transmission, when done right. Look that one up too.

[surfstar]

Originally Posted by redpoint5

Your video doesn't show anything that looks abnormal about the effort required to spin a single wheel.

You are already saving a ton of money by having only a 6 km commute. How much money do you really believe can be saved? I'll do a little math below in units I am most familiar with.

Your commute is 4 miles one way, or 8 miles round trip. Assuming a 5 day work week, you might commute 235 days per year.

8 miles * 235 days = 1880 miles
1880 miles / 18.6 mpg (your mpg) = 101 gal
1880 miles / 21 mpg (EPA mpg) = 90 gal

Assuming $5/gal for petrol, the annual difference is $55 USD, or $0.23 cents per day. You are spending way more money than this just by choosing to lease instead of purchasing a used vehicle from a private seller.

Have you driven this route in other cars before while comparing your mpg with the EPA for that car? You will find that all of them perform below EPA because the distance traveled isn't enough to warm up and run efficiently.

If you want to save money, then ride a bicycle instead. Or purchase a good used vehicle from a private seller. Or install a grill block on your existing vehicle.

Why not jack the other side of your car off the ground and try spinning that wheel? I bet it takes just as much effort to turn. This would mean the brakes and wheel bearings are likely just fine.

THIS post has the answer. A short, cold, commute. Don't waste your time and money looking for a solution to a non-existent problem. $55 per year. One trip to a mechanic to have them "look at your dragging wheels" and you've lost two years of mythical MPG savings.