Improving fuel economy of bigger and smaller vehicles

[pedrobedro]

Why? You'll use more fuel than in gear most of the time.

New cars shut the fuel off when coasting in gear but tickover needs fuel to keep it running.

 

[PhillipM]

2004 Megane 1.5 Dci

Shouldn't be the case at all, if your tripmeter is anything like accurate instead of overdamped, it'd flick to infinity mpg when you lift off in gear.

 

[JMS1972]

Shouldn't be the case at all, if your tripmeter is anything like accurate instead of overdamped, it'd flick to infinity mpg when you lift off in gear.

I agree the Volvo jumps to 99.9 MPG when rolling down hill in gear with the accelerator off.

 

[James1979]

What about a small car / van for daily or long work? I had a diesel Citroen c2 to run alongside my hiab truck a lot of years back. It’s cheap as hell to run and tax. I picked a C2 because the van version is simply a car with no back seats and a tray that bolts in to provide a level, flat load bay and a dog guard that also bolts in.

If you’ve commercial insurance it won’t cost much extra to add.

 

[arther dailey]

good things to improve mpg. service the thing regular , pay special attention to disc brakes, modern ones having for cheapness sliding calipers, these become stuck/worn/sticky rather than smooth causing brakes to bind slightly ,you will lose mpg there easily, engine oil , use the correct grade /viscocity , hand brake adjustment all to easy to have it them slightly tight ,I get 38.9 according to the dash which probably means about 33/35 in real life out of a 4x4 pick thats a working truck ,cant complain at that from a 07 truck.

 

[ajlelectronics]

Always coast in neutral/tickover, when traveling on any downhill

That is what I used to do when I had just passed my test. Until going down a country track in winter, lost it on ice before correcting it and then finding the only pole on the whole track to embed the car into. Taught me a valuable lesson.

It was my first car, a Ford Anglia. When I cut it up for scrap, I found a can of baked beans inside the inner rear wing that must have been put there during the build.

 

[finyuk2005]

I find having a boost gauge installed helps, if you watch the boost and try and keep it as low as possible whilst still maintaining a decent speed its best for economy,
less boost = less fuel being injected
also a remap might help a lot, more torque to waft along without having to rag the engine seems to help,
the difference in my old vw T4s before and after tweeking the pump and turbo was massive!

 

[Gareth J]

Not according to my mpg meter

Regarding coasting, employed well, it can make a positive difference, even on a newer vehicle.

Yes, modern cars shut off fuel altogether on engine braking but equally, engine braking slows you down. There's a point at which, if the extra momentum gained by coasting is worth more than fuel used to keep the engine idling, you've a net benefit from coasting a bit. Imagine cresting a hill which drops into a valley and crests another hill that's slightly lower than the first crest. If you coast all the way, you can carry enough momentum to crest the second hill at a sensible speed. The whole episode has cost whatever fuel it took you to idle all the way.

The flip side, tou leve it in the topest gear to try to keep revs to a minimum (the fact you do this should hint at the inefficiencies of rotating the engine at a higher speed than needed), you use zero fuel on the downhill but engine braking has reduced the speed you hit the valley bottom. Part way up the other side, you engage throttle to make it over the next crest and use more than the amount of fuel you would've done just idling.

Deciding at what point the net benefit tips one way or the other though is, without lots of testing and more information than is practicable to have and process while driving, rather a seat of the pants guess at best!

 

[Munkul]

I used to try all sorts on a weekly trip to Barrow, in a Bora 1.9tdi... best i got out of it was an indicated 80mpg between Barrow and the motorway including starting from cold... coasting down the hills in neutral worked really well there as the hills were huge... theres one dual carriage way on the way back round a corner downhill that coasting speeds would pick up to about 90mph, and it would coast for the next 2 miles if you managed to negotiate the roundabout without braking

I'm thinking more and more about changing car, from my XFS to a golf GTD I'd save over £1000/year in fuel!

 

[Morrisman]

Try to never use the brakes

The front brake pads on my BMW bike lasted me 45,000 miles. Just changed them this summer. I rarely use brakes much, but prefer to just use engine braking into bends etc. Mind you, I’m hardly a Bazza Sheena on my bike at the best of times.

I get around 50mpg from it,1100cc.

Also get 50mpg from my Diseasel Mondeo 1600.

 

[Migmac]

We have an L200, runs On BFG mud terrains. Fuel consumption is pretty much the same as when we had much less aggressive tyres on. We’ve had it remapped from 170 to 250 ish. Fuel consumption has remained the same, grin factor has increased though. My driving style gets me up to 42mpg. Sons is less, he likes the grin factor a lot !

My Ranger on the other hand is getting worse, it’s getting 18.1 mpg. Over a £100 a fill.

 

[ajlelectronics]

I have a reliable 50MPG from my K1200LT. It is always fed 97RON though.

 

[steveo3002]

Always coast in neutral/tickover, when traveling on any downhill

modern ....say early 90s onwards cars will cut all fuel in overun so best let the ecu do the work

 

[Mr Fro]

You'd think the opposite would be the case, tailgate on a pickup would act like air brake? Who knows I'm not a wind tunnel technician.

That's why I remember it (I think!).

I think they suggested that having the tailgate up created a cushion of static air in the bed, thus aiding the aerodynamics.

 

[Aerohead]

Lot of good ideas here, have found anticipating traffic and rarely using the brakes and finding the ideal economy speed make a real difference.
Many memories of driving a performance car across France on N roads and passing all the diesel small cars in the late evening with their lights off, and then they all try to pass me in the village as they attempt to not leave top gear or use their brakes at all...

On a high miles driven large vehicle I have reliably measured a few percentage mpg gains from hotter thermostat temp, and also using a Liquid Moly type product in the gearbox and diff.

 

[Munkul]

I have reliably measured a few percentage mpg gains from hotter thermostat temp

Yes, this! Made a massive difference to older BMW 6 cyl diesel engines, the thermostats all slowly lost strength in them. Swap the 3 stats - get back 5mpg. I've been tempted to try this on the XF but it's a ballache of a job and not cheap either.

 

[Ton-up]

My BIL used to drive all over the country delivering cars. One day he drove me down the M6 in my diesel Passat and annoyed the hell out of me because he pulsed the throttle, not losing any speed, but just on for a few seconds, off for a few, on for a few, etc. When I moaned about it, he said he did it to save fuel, and sure enough the trip had gone up from mid 50's for me to mid 60's for him!

 

[Mr Fro]

My BIL used to drive all over the country delivering cars. One day he drove me down the M6 in my diesel Passat and annoyed the hell out of me because he pulsed the throttle, not losing any speed, but just on for a few seconds, off for a few, on for a few, etc. When I moaned about it, he said he did it to save fuel, and sure enough the trip had gone up from mid 50's for me to mid 60's for him!

That shouldn't work.

Moving an body through a fluid at a certain speed takes an amount of energy. Applying energy in busts will average out at the same amount as a constant application otherwise the body will accelerate or decelerate.

 

[Munkul]

That shouldn't work.

Moving an body through a fluid at a certain speed takes an amount of energy. Applying energy in busts will average out at the same amount as a constant application otherwise the body will accelerate or decelerate.

it depends on the engine efficiency at low loads vs high loads... it may well be more efficient at high loads than small smooth loads.

It also might just be confusing the mpg calculator if it can't keep up with instantaneous fuel rates...

Either way, my mate proved it to me also, but its a horrible way to travel

 

[James1979]

It also might just be confusing the mpg calculator if it can't keep up with instantaneous fuel rates...

That’s what I wondered