Do you hypermile

[RaceDiagnostics]

I used to try to in my daily, but then I get bored and end up putting my foot down.

If i'm I'm the BMW (1800kg, 3.0 auto) there's really no point

I get bored doing the commute, hypermiling relives the boredom.

 

[RaceDiagnostics]

I was doing a 120 mile daily commute. I drove as efficiently as the conditions would allow but I never "Hyper-miled", that's just a step too obsessive for me.

N.B: Coasting still uses fuel to keep the engine at idle, you're better off just keeping off the accelerator in a modern, ECU controlled car, it shuts off the fuel as it doesn't need it to idle whilst in motion.

If you need to slow down put it in gear, thats best , if you don'y want to slow down the get into neutral, then get better mpg.

 

[RaceDiagnostics]

I seldom use the brakes on the 'open road' but will in preference to the g/box, on the basis that, satisfying as manual changing is, brake components are cheaper and easier to replace than a clutch and/or DMF.

Using the gearbox to slow down cuts the fuel entirely so better mpg.

 

[RaceDiagnostics]

I find all the modern diesels have very little engine braking now!
I think it's a bit dangerous as on a motorway you sometimes need to loose a bit of speed but don't want to brake and cause the cars behind to brake when they serve brake lights up ahead. A bit of engine braking g would sort it out though.

NB my new Ford Courier takes up to 2 seconds to give any engine braking at 70mph at lower speeds it comes in a bit quicker.

Mine produces engine braking just fine at all speeds.

 

[RaceDiagnostics]

I have managed 55mpg from a full tank on a 106 gti before. That is miracle territory.

Anyway life is too short and I don't waste my time on such things anymore.

BTW those trip computers on cars telling you how you are doing are not that accurate. The far more accurate way is to use the odometer and without pulling a load of crap through the engine use the low fuel light as the set point.

As already mentioned coasting in modern cars can actually use more fuel than it saves.

Only at really low speeds on mine.

 

[RaceDiagnostics]

Just back from a bender at the pub so apologies if I offended anyone.

Shame about the XK8, it reads constantly as 21mpg.

And the 450SL, I never measure cos its so bad.

 

[wookie]

I've used live data and never seen anything g to indicate they shut off fully

I think that older range rovers cut fuel on the overrun

Using the gearbox to slow down cuts the fuel entirely so better mpg.

The Peugeot 306 Hdi does stop injecting fuel on the overrun, I've used Peugeot Planet 2000 software and it shows how many cc's are injected into each cylinder for each cycle (I used the logging function and went for a drive) and on the overrun the cc's drop to zero, also if you then press the clutch down it has to start injecting just enough to idle the engine otherwise it would stall because the wheels are no longer driving the engine.

 

[the snooper]

The Peugeot 306 Hdi does stop injecting fuel on the overrun, I've used Peugeot Planet 2000 software and it shows how many cc's are injected into each cylinder for each cycle (I used the logging function and went for a drive) and on the overrun the cc's drop to zero, also if you then press the clutch down it has to start injecting just enough to idle the engine otherwise it would stall because the wheels are no longer driving the engine.

I think I'm going to test this theory, if the fuel is totally shut off turning the ignition off will make no difference what so ever if however a difference is detected then it must still be fueling the engine

 

[Crater Creator]

I think I'm going to test this theory, if the fuel is totally shut off turning the ignition off will make no difference what so ever if however a difference is detected then it must still be fueling the engine

Snooper, that might not be a conclusive test though - turning the ignition off will make a difference anyway, the throttle valve (and maybe EGR) is generally electronically controlled and you will cut the power to them, changing the engine intake vacuum and braking effect. If you could cut off only the spark then yes the test would be valid.
I think the logging of the port is a more reliable indicator though.

 

[Gritineye]

The lady conducting my speed awareness course told us it's a good idea to use the gear that matched the speed limit, 2nd in a 20mph zone, 3rd in a 30 zone and so on.

Of course someone said 'That'll use loads of fuel, my husband won't allow it'.

The lady said all fuel injected cars are made to be driven like that, the ecu will adjust the fueling to the need and mpg will stay the same.

Can anyone familiar with these things confirm this?

I find the trick does work very well if I can remember to do it, anyway whats a little fuel if it stops point and fines..

 

[8ob]

I've used live data and never seen anything g to indicate they shut off fully

I spent a few days with Dave Walker while he dynoed/mapped some silly engines for me using one of his Emerald cams programmable ecu`s. The fuelling map from 7000rpm down to 1000rpm on a released throttle has no numbers dialed in, so no fuel injects until the engine hits 1000rp on a released throttle. Fuel consumption in this case was not the issue but more for engine braking , that said there is no sense mapping unwanted fuel in on so the two would go hand in hand.

Bob

Beast

 

[Cobbler]

The lady conducting my speed awareness course told us it's a good idea to use the gear that matched the speed limit, 2nd in a 20mph zone, 3rd in a 30 zone and so on.

Of course someone said 'That'll use loads of fuel, my husband won't allow it'.

The lady said all fuel injected cars are made to be driven like that, the ecu will adjust the fueling to the need and mpg will stay the same.

Can anyone familiar with these things confirm this?

I find the trick does work very well if I can remember to do it, anyway whats a little fuel if it stops point and fines..

My diesel Skoda Roomster, according to the obc uses considerably more fuel in the lower gears to do the same speed. With a petrol engine I don't feel it's so marked, but can't confirm it. Years ago I had a car that lost top gear, for a while I drove it around in third & it didn't seem to make a lot of difference. This had an SU carb, don't know about modern injected stuff.

 

[Shox Dr]

My diesel Skoda Roomster, according to the obc uses considerably more fuel in the lower gears to do the same speed.

Its bound to the rpm will be higher

 

[daleyd]

Does this theory apply to diesels ?

I would guess so, one thing to remember is when you lift off generally you'll be in a high gear so the engine braking effect will be a lot less than in lower gears, where the effect is really noticeable.

 

[Lufbramatt]

The lady conducting my speed awareness course told us it's a good idea to use the gear that matched the speed limit, 2nd in a 20mph zone, 3rd in a 30 zone and so on.

Of course someone said 'That'll use loads of fuel, my husband won't allow it'.

The lady said all fuel injected cars are made to be driven like that, the ecu will adjust the fueling to the need and mpg will stay the same.

Can anyone familiar with these things confirm this?

I find the trick does work very well if I can remember to do it, anyway whats a little fuel if it stops point and fines..

Shes talking nonsense

The ECU aims to maintain a set air-fuel ratio, in a lower gear the engine is turning faster and sucks in more air. So you have to stick more fuel in to compensate.

 

[mike os]

Life is too short..

 

[Crater Creator]

Shes talking nonsense

The ECU aims to maintain a set air-fuel ratio, in a lower gear the engine is turning faster and sucks in more air. So you have to stick more fuel in to compensate.

Depends on the throttle valve position. On the overrun (at any rpm) the throttle will be closed and the engine will be sucking in very little air.

You will have more frictional losses at higher rpm but every engine will have a best-efficiency point in the rev range, either under or over that will get less mpg.

 

[Gareth J]

Depends on the throttle valve position. On the overrun (at any rpm) the throttle will be closed and the engine will be sucking in very little air.

You will have more frictional losses at higher rpm but every engine will have a best-efficiency point in the rev range, either under or over that will get less mpg.

Diesels don't have a throttle. On the overun, they're just an air pump. Add in the restrictions in the exhaust (cat, dpf) and higher rpm generally means more work being done. The lower your rpm, the less air volume you have to pump per minute through a restricted pipe.

I don't know the intricacies of the speed awareness course but am guessing that pointing out the teacher is wrong isn't the best plan. I was thinking dumb, solemn compliance regardless of how daft it is will get proceedings over with the minimum of fuss and hassle. I'll find out soon enough.

 

[rtbcomp]

My 24 year old Volvo has a fuel economiser option (not fitted to my vehicle). It's a black box which takes vehicle speed and engine rpm and puts a light on to tell you to change up. There is a clutch switch, presumably to cancel the warning light when the gear change is made.

I don't see why modern cars shouldn't have a clutch switch to keep the engine running when you take your foot off the gas to change gear.

 

[Swift&Bold]

I don't see why modern cars shouldn't have a clutch switch to keep the engine running when you take your foot off the gas to change gear.

They will if cruise control is fitted but they don't really need a switch to monitor if the clutch is in or out, there are many other clever ways the ECU can tell by detecting the load on the engine compared to the road speed and revs or by using "Knock" detectors on the injectors, it's often underestimated how much processing power the ECU of a modern car has.