Economical Driving

Economical Driving - The Physics
Economical Driving
Head Injury

Manufacturers' fuel consumption statistics are (simplistically) at a constant (rolling road) speed or, so it would appear, 90 km for 60 minutes = 90kmph (56mph). Figures like this are quoted at one speed only and are totally unrepresentative of reality. There is considerable variance between 30kmph, 60kmph and 90kmph. Only at constant speed on long journeys is the best fuel economy returned if the speed is kept between 96-112kmph or 60-70mph (approx) and if the legal fastest top speed [112kmph or 70mph in the UQ (aka UK) Ltd] is not exceeded. Drive faster and illegally, the cost overhead is huge. The heavier the car, the more the cost overhead. Up to x22.5 or possibly more depending on how heavy the right foot is. Most driving involves stop/start/slow/accelerate/brake/stop/start... etc. Considerably variable conditions

Distance Tax - Update
PetrolPrices.com

Overall, the actual fuel consumed and 'official' statistics are very misleading. Not necessarily anything untrue, but massaged and distorted to provide favourable (to the manufacturer) statistics. Petrol as a fuel is increasing in price and as always, regardless of any shortage or glut. It seems as though an arbitrary decision has been made (somewhere!) to screw the global population as with other energy sources. When diesel as a fuel became popular in the UQ (aka UK) Ltd, it was considerably cheaper than petrol. Not surprisingly, time saw the price of diesel rise and is currently a similar cost to petrol.

Diesel or Petrol
Differences

It is possible that people are realising (at last) that owning an expensive vehicle is affordable, but running such a vehicle is not. Psychologically, it is common for someone to keep a product even though the 'hype' does not live up to reality.

How many users actually do an analysis
of petrol/diesel usage and monitor
their driving technique accordingly?

If you have on-board fuel status system, especially if it updates regularly, it is an education to monitor how fuel consumption varies significantly depending on driving technique. Revs for the gear selected have a great impact on mpg. It is an education. Translating the mpg into £pm is then very enlightening. The overall cost for a day, week or month can be a real wake-up call if there are concerns about the cost of fuel. For the environmentally aware, the wastage of a dwindling resource due to careless driving techniques should shock.

The sales of forever better performance vehicles is maybe in decline and car manufacturers are developing better diesel engines. The return (mpg or litres/100km) used to be better even though the cost of the fuel is now roughly the same. Performance diesel-powered engines are now not much better than an efficient petrol-powered small engine. The distinction between diesel and petrol appears to be decreasing as performance improves.

It is a curious perception that even though an explosive air/petrol vapour mixture of constant energy yield apparently translates into more or less power irrespective of the vehicle size and weight. The misconception is created by the manufacturers' performance data. Selectively presented to produce the illusion of difference. How can a 2-tonne vehicle produce the same economies as a 1-tonne vehicle. It cannot, so the driving techniques and conditions that produce these figures are highly contentious. But this sells cars. Even more bizarrely, some of those who complain about high fuel costs do not consider driving more economically. They contribute to a financial problem and may possess the answer to their own problems.

• It's instructive to observe drivers (especially women driving powerful cars) negotiating bends. Power steering cannot assist heavy cars negotiating bends. The vehicle moves comfortably in a straight line, but move out of true and the forces attempting to roll the car are quickly realised (Newton's 1st law of motion). Turning at speed requires considerable strength regardless of any power assistance.

Green Car Guide

Police spec XF: May 27 2009 (2.7 Diesel) currently (2010) a 3L model with identical results, but kerb weight unspecified.

• "The Jaguar XF Diesel, especially in new S form, would be an ideal pursuit car." The new, higher power XF cranks out a stolid 271bhp and ticks all the key detective criteria: 0-60mph in 5.9sec, combined economy of 42mpg and 179g/km CO2

So, after removing all the irrelevant equipment (for policing operations) the current production (diesel) Jaguar is the police performance car of one year earlier.

The sales of diesel engined cars also appears to be expected to increase with a concomitant decline in petrol-powered car sales and it shouldn't be long until the cost of diesel fuel substantially overtakes that of petrol. In any event, the selfish wealthy individuals who imagine themselves to be able to 'afford' to finance any obscenely thirsty vehicles are consuming an evermore valuable resource. For every wealthy individual that can finance driving at 70mph -> 80mph -> 90mph -> ... and consume (destroy) enough fuel in a week that could allow a smaller car to operate for several months, the oil wells get closer to inevitable exhaustion.

When in a desert conserving water is vital and a rich man will die of thirst as quickly as a poor man.

Small Bites (Philosophical):

• 215. What is the purpose of life? How is success measured? What does one need to do in order to be 'successful', but whose definition: rich man or poor man? What is wealth: money in the bank or novel ideas in the mind? It is only the exploitation of an idea that can make money. It may be a physical or intellectual idea, but is still just an idea or concept. Without an idea nothing can happen. A man who has a financial fortune (from where?) may be absolutely devoid of ideas. A man rich with ideas may develop financial wealth from ideas, but the creation of the idea of an individual can never be bought by that individual as it doesn't exist until it's created (free) in the mind. It's the (huge) difference between an Einstein and a Rockerfeller (Wealth And Power). Like the Sun and the Moon.