Disappointing highway mileage.

[JockoT]

Did a bit more looking, in case I had missed something. The Ford Eco-boost came out in 2010. The newest car I was able to afford was a 90K miles 2006. The PSA 1.0 litre engine develops even less bhp and torque than my 1.2 Jazz.
I was pretty much between a rock and a hard place when I purchased the Jazz. I needed a roomy 4 door car, cheap to rum and not too steep to tax and I had £1500 to spend. Kind of limits your choices.
The original title of this thread "Disappointing highway mileage." doesn't refer to the actual mileage I am achieving. I am delighted with that. I am disappointed that, once I had the benefit of the ScanGauge and the knowledge base here, I was not able to make much difference to my highway consumption.

[R.I.D.E.]

At those speeds engine off coasting is your best tool for significant improvement. Bottom line, when utilized properly, it should make a significant difference. I run 50 psi in my tires which makes a small difference over 44 psi. I share your situation, I have a limited monthly income, but significant assets. No loan payments, house paid for 20 years ago. A little money goes a long way when you aren't paying for your house and car.

[JockoT]

The problem with the Jazz is it is so light so has very little inertia. On the dual carriageways we have around here you have to at least maintain the speed of the artics (semis). They run at 50 mph, sometimes more (I am happy for the faster ones to have to go round me). So if I accelerate up to 60 then coast back to 50, engine on or engine off, it only lasts a few seconds. It makes for a more comfortable journey just to sit at 50 and tuck in two seconds behind a truck. That way you don't get tooted at and you get the advantage of a bit of a tow.
The reason I don't do engine off coasting is my electric power steering has a huge effect. Without it, the steering is frighteningly heavy. Add to that a fierce clutch and it makes engine on coasting my method of choice

[Draigflag]

Personaly I wouldn't risk breaking the law, voiding your insurance and compromising the safety of yourself and other road users for the sake of a few pence worth of fuel. Your pension isn't that bad I'm sure

[JockoT]

Originally Posted by Draigflag

Personaly I wouldn't risk breaking the law, voiding your insurance and compromising the safety of yourself and other road users for the sake of a few pence worth of fuel. Your pension isn't that bad I'm sure

Me neither. That's why I don't.

[JockoT]

Visited a mates farm today, where there is a long, descent on a nice private lane. Visibility was great, and with nothing else to hit except growing wheat I decided to try EOC. At higher speeds the steering was really quite manageable. No worse than some of the non power steering cars I have owned in the past (not as heavy as my SAAB 99). I had left the car in gear, depressed the clutch, turned ignition off then back on again, and coasted like that. As soon as I needed to, I just lifted the clutch and the engine started. I didn't particularly enjoy the experience and don't think I would consider it out on the open road. I don't feel that I do enough highway miles for it to make an appreciable improvement to my overall mileage figure.

[R.I.D.E.]

It was illegal in Virginia, coasting with the engine off, but they stand on weak grounds as far as legal precedence when a Prius does the same thing automatically and almost any time you're driving one. (EOC)

In the early 1930s, Plymouth brought out freewheeling in the USA and with the pitiful brakes of the era long downhill slops in the mountains could cause loss of braking and wrecks without the engine drag to help in the long (several mile) descents.

The steering is boosted (electric) on my car and it is useless and unnecessary at any speed over 5 mph, as at the over boosted (vacuum with a reservoir) brakes, but then I ride my bicycle 12 miles daily. I've driven a lot worse that had no assist for steering or brakes, try 5.2 turns, lock to lock, manual in a 63 Valiant, but it got 28 mpg highway. A convertible Valiant I had would not leak in a car wash, and it would literally fly through the air for 40 feet and not even lose front end alignment after bottoming out the front crossmember on asphalt, after hitting a short 3 foot hill at 55 mph.

Do that in anything you drive today and it's totaled, easily.

[trollbait]

Sounds like your Fit/Jazz is suffering from the same issue 5spd manuals here do in not having a tall enough gear for cruising at real world highway speeds. The 6spd manual and automatic in the Sonic/Aveo has the car pulling under 2000rpms at 60mph with the 1.4L turbo.

I know it is possible to swap out the gears in the transmission, but I suspect it isn't a cost you wish to undertake. Same with upgrading to a 6spd transmission from a newer Honda. When the time comes for new tires, going with a size that has a taller side wall will help a little in bringing down the rpms while cruising.

Boxy hatchbacks tend not to have the best aerodynamics, so modifications there will help at highway speeds. Outside EOC, I have found that the other driving techniques don't offer much improvement over simply driving sensibly at highway speeds with small displacement cars.

Unless my Sonic is simply easier to turn without power steering, the electric steering assist can still be on while EOCing. Same with the vacuum pump and accumilator for the brakes a diesel will have.

[JockoT]

The Jazz would certainly benefit from a 6th gear (I remember when 3 gears was considered sufficient), but it is not under-geared. 60 mph is only about 2500 - 2800 rpm. The problem with higher gearing is the tiny engine doesn't have the power to accommodate it. It needs the gearing it has to accelerate successfully.
The current tyres have the tallest profile I can get (175/65T14).
My model Honda Jazz requires the engine running for the power steering to work. The ignition on doesn't do it.
As for bodywork mods, I'm not that way inclined. I need both my exterior mirrors and two wiper blades and I am not that desperate for more mpg that I'd go to the extent of an under-body tray or airdam.

[trollbait]

I was thinking more of a boat tail, but the testing and fabrication is a hassle.
A basic air dam can be easy. A past car had a plastic lip hanging down from the bumper under panel. I just screwed a length of flexible garden edging to it. It wasn't at the ideal spot, but also wasn't as noticable.

If you were already driving in an efficient manner, a scangauge just isn't going to help much with steady state cruising unfortunately.