Hypermiling

[ExigeEvan]

@Bopop4 - I'm pretty sure it depends on the decline. If the engine braking is overcome by the slope then it's certainly better to leave it in gear?

Pulse and glide, then I'd imagine neutral.

 

[lbpomg95]

@Bopop4 - I'm pretty sure it depends on the decline. If the engine braking is overcome by the slope then it's certainly better to leave it in gear?

Pulse and glide, then I'd imagine neutral.

That's the way I look at it. In gear 5, there isn't much engine braking at all in my car at anything below, say 35mph. Since it's a pretty basic engine, leaving it in gear has helped greatly.

That said, you can use engine braking to an advantage when it comes to stopping for a red light, changing down every gear and such. I also rev match when changing down to stop the clutch wearing as much but that shouldn't make a difference to MPG.

 

[Bopop4]

@Bopop4 - I'm pretty sure it depends on the decline. If the engine braking is overcome by the slope then it's certainly better to leave it in gear?

Pulse and glide, then I'd imagine neutral.

If there was a hill then you would gain a ton more speed in neutral. You could then use it for a longer glide.

Only thing I've found engine braking good for is if there's a stop at a bottom of a hill.

 

[Leggy1]

That's the way I look at it. In gear 5, there isn't much engine braking at all in my car at anything below, say 35mph. Since it's a pretty basic engine, leaving it in gear has helped greatly.

The higher the revs, the higher the engine braking effect. In 3rd at the same speed there would be a lot more.

 

[lbpomg95]

The higher the revs, the higher the engine braking effect. In 3rd at the same speed there would be a lot more.

I'm aware, hence I said gear 5, not 2.

 

[ExigeEvan]

So, filled it up today. 855.59 km on the last tank, and 66.63 Imp MPG, from 36.3 litres, and fuel light wasn't long on and 50 miles left on the computer. There's another 2 gallons in the tank at that point, though some people claim they can fill upto 50 litres.

1000 km tank should be easy with a bit of blind faith.

 

[W3H5]

Couldn't you attach a sail to your roof and raise it every time you get a tail wind?

 

[mustafur]

Delete​

 

[niky]

Personally, engine braking is only worth it if you have way too much momentum going downhill or are coming to a stop.

Here's an interesting take on it:

https://www.hs-heilbronn.de/5023311/coasting-on-highways.pdf

The paper basically shows that pulse & glide, with neutral coasting, is better than not coasting in neutral.

And that Engine-off strategies are better than anything else, to the tune of about 5-10%. Of course, you have legal and safety issues with EOC, though it's worth noting that this is specifically something that hybrids do to save gas. (Hybrids, however, use electric power steering and regenerative braking to overcome the two most worried about negatives of EOC... mainly loss of steering assist and loss of brake vacuum).

 

[homeforsummer]

1000 km tank should be easy with a bit of blind faith.

Should be easy for me too, in theory, with a 40 litre fuel tank (8.8 UK gallons, 10.6 US gallons).

621 miles on 8.8 gallons? I'd need to do 70.5mpg. I've done that lots of times, but have never had the guts to see how far I can go on a tank. My best so far has been 81.3mpg (715.4 miles or over 1150km) but on that tank I only did 525 miles before filling up.

The longest I've gone on one tank is 594 miles (956km) at 77.7mpg.

Ultimately, my fuel tank is always a lot bigger than I think it is. On that last described fill, I was down to the last sliver on the LCD fuel gauge out of I believe around 20 little slivers, which to me was cutting it a bit fine. But if I eked out every last drop on that fill, I had another 89 miles of fuel left.

 

[ExigeEvan]

360 miles done, 250 on the computer remain, and I have a good idea of my travel for the rest of the week.

This should comfortably be my 1000km tank. I hope.

[EDIT]

 

[ExigeEvan]

The Fabia made another little achievement today, 75 MPG indicated at the end of the 41 mile journey home from work.

 

[W3H5]

Holy smokes that good. How did you manage that?

 

[ExigeEvan]

Nothing too crazy, just fortunate with traffic lights (there's 2 chains that I rarely get through clean, one at bottom of hill and the other just off motorway. Both huge momentum killers), topography and some mad skills. The final stretch home was tough but I managed to squeeze a cheeky coast and burn on the last mile to the house without holding up traffic.

Oh and no aircon. It was just about cool enough to go without!

 

[W3H5]

Aircon is probably the biggest sap on my fuel tank. I don't mind having the window cracked a little (with a visor type thing at the top making the airflow a bit cleaner) but my wife feels like she needs it to breath. Typical woman costing me excess money...

 

[niky]

Aircon is probably the biggest sap on my fuel tank. I don't mind having the window cracked a little (with a visor type thing at the top making the airflow a bit cleaner) but my wife feels like she needs it to breath. Typical woman costing me excess money...

With our climate, AC is a necessity. I only get to turn it off when driving solo.

Speaking of AC off driving:

That's a combined 91 mpg-uk (76 mpg-us). But half of it was downhill. On the level portion, I managed that 4.0... (71 mpg-uk, 58.8 US) half of it in traffic. (those big vertical bars on the "This Drive"screen)

And that's with an automatic transmission. I know, I know... onboard is not always accurate, but I'm pretty pleased I actually made it the thirty or so kilometers home on the fumes at the bottom of the tank.

Gasoline engine, to boot.

 

[ExigeEvan]

Great job 👍 What car is that?

I've had several chats with my new boss about cars, but it's very Jekyll and Hide. One minute it's 75 mpg in his new Polo Bluemotion, next it's the £800 tyres for his Cayman.

 

[niky]

Mazda2 hatch. Was hoping for better, but this thing has heavy 16" wheels and a stubby shape... Not as aerodynamic as a sedan.

1.5 6AT. Could use a longer sixth, but at least, like all Mazda ATs, you get full control and can lug it at just over idle.

Left a lot on the table. Didn't shut off the engine to coast to lights or when waiting in traffic. Would have erased the record!

 

[W3H5]

And to think I was considering one of those Mazdas. I do have steels on at the moment so when we switch out to alloys I should lose a bit of unsprung weight, but the little engine in my car is so economical anyway, especially with the limiter engaged. No 6th gear though from what I can tell.

Edit: So after doing some research it appears my CVT is a simulated 7 speed. I guess I haven't been going fast enough.

 

[niky]

And to think I was considering one of those Mazdas. I do have steels on at the moment so when we switch out to alloys I should lose a bit of unsprung weight, but the little engine in my car is so economical anyway, especially with the limiter engaged. No 6th gear though from what I can tell.

Higher end CVT variants get a seven-speed mode, but the virtual "7th gear" is shorter than the final drive in full-auto.

The Honda CVT should have better highway legs than the Mazda 6AT... but I must admit, I haven't driven the (new) Mazda2 sedan yet, which should get better economy than the hatch.

These Mazdas are absolutely fantastic to drive. Too bad the back seat is still a shade too small.

 

[W3H5]

If I keep it under 60mph on the highway it returns good mileage but the stop-start city traffic doesn't do it any favours. I've got around 300km to do tomorrow, about 80% is out of town cruising so I'll reset the meter and see what I can manage if I go gentle.

 

[Mikeybc]

Higher end CVT variants get a seven-speed mode, but the virtual "7th gear" is shorter than the final drive in full-auto.

That's exactly what I found with the Murano, when running along the highway in "7th" then flip it over to "drive" the engine drops about 100 rpm or so. 1200 rpm cruising at 60. Drive around town with a light foot and it won't go much over 1500 rpm.

 

[homeforsummer]

One minute it's 75 mpg in his new Polo Bluemotion

Driven well, I'm led to believe those can be quite impressive.

One of my colleagues commutes from London to the office in a regular Mk3 facelift Polo 1.4 TDI. He gets a regular mid-60s to the gallon plodding up the M1 and has reported 70+ a few times. Basically, it's saving him well over double what it'd cost to do the journey in his Clio RS, plus the wear and tear associated with running a performance car every day.

My Insight is currently for sale, and realistically I won't be replacing it with anything as I just don't have anywhere to keep two cars (three, if I end up getting a long-termer). But I've certainly had thoughts about picking up an Audi A2 1.4 TDI, or a Smart Fortwo CDi, just to see what I could get from them.

At steady speeds below around 60mph, I think the Insight is pretty much unbeatable by any other non-plugin production car, because the lean burn is so effective and below 60mph it's running in lean burn a lot of the time. But at higher speeds, and in transient conditions like going up and down hills like those on my commute, I suspect an ultra-frugal diesel might just beat it. The Smart in particular, since it's even lighter than the A2.

I'm actually a little out of the loop with the latest eco cars. Wonder what could be persuaded to use the least fuel. At lower speeds I suspect the Yaris Hybrid, since they do so well in start-stop conditions. At higher ones... probably still a Polo Bluemotion/Fabia Greenline/Ibiza Ecomotive. Or maybe the diesel Citroen Cactus, which would certainly be one of the less depressing ways of doing mega economy.

 

[ExigeEvan]

Driven well, I'm led to believe those can be quite impressive.

I'm led to believe there's an element of cylinder deactivation that takes place. I'd like to see the results from brimming the tank because I've not seen any evidence yet that modern eco cars deliver the claimed mileage, but I can't say I've really looked either (everyone on UK hypermiler uses their dash figures).

 

[homeforsummer]

I'm led to believe there's an element of cylinder deactivation that takes place. I'd like to see the results from brimming the tank because I've not seen any evidence yet that modern eco cars deliver the claimed mileage, but I can't say I've really looked either (everyone on UK hypermiler uses their dash figures).

I've not actually driven any of the ones that claim ultra-ridiculous numbers, oddly. The two most economical diesels I tried previously were the diesel Smart, and more recently the current 1.6 diesel Civic, which is astonishingly frugal. As in, ~70mpg on a gentle motorway jaunt.

That, and the Scirocco 2.0 TDI I tried a few months ago that averaged 65mpg from Goodwood to Northants. That was in typical M25/M1 slower-moving motorway traffic, rather than a steady 70 or so, but not bad at all for a car that performs like it does. Suspect it's more than the slightly breathless 1.6 TDI would have done too.

Most of the current diesel superminis will do 60mpg fairly easily if you don't drive like a knob. Peugeot/Citroen ones are good.

 

[niky]

@ExigeEvan The ecomodder.com people frown on in-dash figures.... at the very least, they should be backed up by calibrated Scangauge readings (you can adjust for inaccuracies).

Then again, when testing different units, I don't have the luxury of installing instrumentation and calibrating it!

-

@homeforsummer - I wouldn't put much hope in the SMART. Too short for good aero, though it'll likely be fantastic in traffic. A good 1.4 or 1.2 diesel in a sedan body should do the trick on the motorway. Hyundai's motors have always been impressive in terms of economy... but no small Hyundai is as good to drive as the Polo!

 

[homeforsummer]

@homeforsummer - I wouldn't put much hope in the SMART. Too short for good aero, though it'll likely be fantastic in traffic.

I mentioned it from experience - my first ever press car was a Fortwo CDi, and on a motorway run from Newcastle down to Surrey and back it averaged 72mpg (imperial). That was without deliberately driving for economy (like I would in the Insight to get it towards the 80s), but I'm a reasonably economical driver anyway, so it didn't include much real thrashing either. It's not very aerodynamic, but I think the frontal area is relatively small which brings a few points back when you consider CdA.

I suspect on my commute it'd be at least as frugal as the Insight, with the potential to be more so since the Honda doesn't like hills or sustained acceleration (or sustained acceleration up hills).

In pure performance terms, the Honda is quicker than even the higher-output diesel smart*, but the Smart also makes 96lb ft at 2250rpm rather than the Honda's 83lb ft at 1500rpm... provided you're at WOT in the Insight to get the electric motor working to best effect. Like I said, it's a transitional thing - on a flat surface at low throttle loads, I'd be surprised if there's a car around today that could match the Insight, but introduce periods of acceleration, hills etc and there's a lot to be said for a diesel's ability to reach your desired cruising speed relatively swiftly. If they'd brought such things to the UK and they weren't too expensive, the Audi A2 3L would probably be the best compromise - small-diesel economy on a commute, Insight-style aero benefits at higher speeds.

Of course, I still have reservations over the environmental credentials of diesels, but that's a whole other kettle of fish.



* Relative term. They did one with 45bhp initially, then increased it to 54bhp!

 

[W3H5]

I like the sound of the Smart, Hoofs, I'm sure with a few tweets that could do some excellent mileage both in and out of town. Like you say, the Insight was build from the ground to be super efficient and not much if anything will come close to it's figures.

Question - if I'm stopped in traffic and shift to park rather than just leave it in drive and keep my foot on the brake the engine jumps up a few hundred RPM. Is this normal? I would have thought that being in park would result in a lower idle.

Also long drive today ( I hate driving) and apart from the first few km and a drive through McDonald's it'll be all open country roads where I shouldn't need to drop below 50mph. I only have the dash counter to gauge the mpg so I'll see what a light foot can produce using the same techniques I use on my motorcycle; no brakes over 20kph, snail-like acceleration and all tyres over inflated.

 

[W3H5]

Didn't manage much hypermiling due to some fantastic roads I felt the need to race along. Did get a recording from the instrument clock at the end of the trip though but haven't converted it into MPG yet:

527.0km @ 18.2 km/l

...and Google says...

42.8mpg.

Not bad really considering I was thrashing the car up and down hills for 50% of the trip and had to pass through a big city twice.

 

[niky]

Didn't manage much hypermiling due to some fantastic roads I felt the need to race along. Did get a recording from the instrument clock at the end of the trip though but haven't converted it into MPG yet:

527.0km @ 18.2 km/l

...and Google says...

42.8mpg.

Not bad really considering I was thrashing the car up and down hills for 50% of the trip and had to pass through a big city twice.

That's a sight better than the old car. Old car, any amount of hills and your driving average goes way down. You'd be lucky to get 18 in the old Jazz at a steady clip on the highway.