Fuel Economy...& throttle control....

Throttle controll has always been the best improver of economy.

No doubt they will have chosen a couple of "charlies" with lousy driving habits to make the figures look good... but the fact remains.

If you are continuoulsy on and off the throttle and on the brakes you will be wasting fuel....big time

Every time you brake you waste energy you have had to generate with the throttle.

I see people every day, who continue to accelerate up to red lights, sit fair up the clacker of the car in front and are always in a hurry.
Of course they will always be on the brakes, and just as much on the accelerator......alll wasted fuel.

Old Hans knows his stuff..he used to compete in economy runs against the like of Peter Feret and the like...back in the 70's and 80s when they were trendy..and he did well.

The secret ( its no secret) is to sit well back and accelerate only as much as is required to get the job done and no more.

Be on the accelerator early and lightly, keep a consistent throttle opening, button off as soon as things slow down in front and brake as little as possible.

hard acceleration is achieved by pushing more fuel into the engine..it makes more power but is less efficient.
the more preasure you place on your drive train by accelerating the more friction is generated and the more losses occur.

Do everything smoothly and you will save fuel and wear and tear.

AND top speed will mostly be irrelivent in the argument...getting up to that speed smoothly and getting down from it with minimum braking is what matters.

And you will probably pull up right behind the other bloke in the next town.

And ya fuel bills will be lower and you will have brakes that work when you need them.

cheers

Arrhh an ideal world.... wouldn't it be great!

Another Allianz moment.

Any one can drive for efficiency but in the real world is it practical.... no.

Unless you want to annoy every other road user behind you.

Classic examples...
Travelling at 80Kph in a 100Kph zone.
Slowing down and rolling up to traffic lights.
Taking of slowly from a stop.
Slowing down prematurely to avoid using brakes.
Coasting up hills.

Most who drive like these examples usually have all the time in the world and are inconsiderate to other road users... with a mind set that they own the road and can do what they want.

Drive sensibly and what your vehicle uses it uses.

From High School Physics; energy expended is equal to force times distance. The distance remains the same but the force increases dramatically with speed, so you would expect the consumption to increase dramatically with speed.

See Car Aerodynamics for interesting information on car aerodynamics.

See Caravan Aerodynamics for You Tube video of caravan aerodynamics. There are two parts to this.

There is something they are not telling Oldbaz and that is that their is a sweet spot for fuel efficentcy out of any engine and further that this sweet spot shifts a little as it is load dependant,

You can actually drive faster under specific conditions and get the engine into a more efficent range and actually reduce fuel use (the speed though tends to be sub 85 and wind effects.).

If you find this for your car you will improve -> roughly 1700 - 2000 rpm for typical petrol engines.

Once apon a time you may remember the economy guages on some cars (holdens) which isn't the full answer part is part thereof.
Julian , the guy from Silicon chip wrote some quite comprehensive articles about this - on the web somewhere , think from autospeed ?

Driving efficiently does not automaticaly mean you are driving slowly.

Mashing the accelerator so you can get up to speed on the highway is pretty pointless...unless you are trying to enter a high speed traffic stream.

Most engines and vehicle have sweet spots ..some have one some have several.

If the engine torque and power curves are matched with the gearing properly the sweet spots will be close to the legal highway speeds.

Usually the most efficient highway speed coresponds to the peak in the torque curve.

My old 808 waggon liked about 95KPH...but it liked 120KPH better...ah those were the days.

As far as cruse controll being less efficient....I believe that is a gross over generalisation.

A well designed cruse controll will maintain a consistent throttle opening and moderate throttle increases.

A well designed cruse controll in a vehicle with ample power and lightly loaded will return excelent fuel economy results on good open road......the cruse controll in the wifes RAV does an excelent job....I don't think I could do better.

A poorly designed cruse controll in a heavily loaded vehicle running on hilly terain will do quite badly....but you should driving manually then anyway.

As far as people doing 80KPH on the highway.......most regular highway users will agree that they are an inconsiderate menace....ya just have to hear the abuse on channel 40.

If your rig will not tow safely at 100KPH on the highway, it should not be on the road.

Sure you might be slowed down by hills and such, but you should be able to maintain at least 90 to 95KPH and ya 100KPH with a bit of luck and good terain, on reasonable open road.
These at that days lots of people will happily sit behind you till a good clear pasing oportunity presents

If you are driving at 80KPH on the open highway simply to save fuel.....you are nothing but inconsiderate, your saving is at the much greater cost of others in time and fuel.

Have some consideration for the heavy vehicle driver who at 100KPH would happily roll on up that long hill and top the crest efficiently at arround 90KPH in top gear.
But because he is stuck behind you doing 80KPH, he has lose momentum to lug up that hill, and then have to do arround 6 to 10 gear changes and crest that hill doing 60 to 70KPH......this then holds up everybody behind.....and the whole BULL$#@& magnifies as you get back further in the line.

Traveling at 80KPH might be saving you $5 to $10 a tank full, but you are probaly costing every truckie behind you $5 to $10 a hill and pissing off dozens of other highway users every day.

Perhaps you should have baught a smaller van.

cheers