PowerSwitch

Ministers are planning to crack down on motorists who speed on motorways in an attempt to meet government targets aimed at reducing Britain's emissions of greenhouse gases.
Officials acknowledge that any move to force the 15 million motorists who currently exceed the 70 mph speed limit to slow down would be "politically sensitive", but they say it would save significant amounts of carbon dioxide pollution. Engine efficiency falls quickly beyond 70 mph

http://politics.guardian.co.uk/homeaffa ... 46,00.html

For climate change...or in anticipation of something else?

On my jouney to my previous place of work, driving at 75-80mph when I could got me 55mpg. When I slowed down to 60-65mph, I got 65mpg. It's definitely worth it, and might start getting us used to having to cope with less travel.

I can vouch for similar savings, 55mph in my diesel skoda uses about 80% of the fuel that 80mph does.

I find that I am currently achieving approx 40 mpg on milk and cornflakes, with an average speed of 18 mph (a bit more if I peddle harder).

Ballard wrote:I find that I am currently achieving approx 40 mpg on milk and cornflakes, with an average speed of 18 mph (a bit more if I peddle harder).

Maybe you should try weetabix

Did you notice the other measures mentioned in the article?

It also weighs up what it calls "politically difficult" options, which include road-user charging, changes to speed limits, high-speed rail links and reintroducing double British summertime - where the clocks go forward two hours in spring.

Quite neat how all these measures would help deal with declining North Sea oil, whatever the reasons given are... I wonder if they'll implement them?

Engine efficiency falls quickly beyond 70 mph

All engines have an optimum RPM but wind resistance has a lot to do with it. fairly insignificant at 30mph. Pretty significant at 70mph, and ramping up rapidly. Eventually highly singnificant at the vehicles top speed - wind resistance and other frictional effects balancing forward motive force from the engine

Other suggestions... engines which automatically switch off when a car is stationary for more than a few seconds.. I think I read that this is now obligatory for cars sold in Switzerland (dont quote me)

one Ive suggested before, which I see is being introduced by the Chinese. A sliding scale car tax, inversely proportional to fuel efficiency.

" A few months ago, Premier Wen Jiabao urged "all regulations that suppress the development of economy cars be dropped" as part of efforts to build an "energy-saving society."

CHINESE BUYERS OF SMALL CARS TO ENJOY BIG TAX BREAKS
http://au.biz.yahoo.com/051109/17/cv07.html

somebody ought to have a word with Bush and Cheney about that

I must admit that although I now normally cruise at 50MPH or so (nice easy drive in the left hand lane without having to undertake middle/outside lane hoggers) I occasionally feel the urge to speed knowing that "I probably won't be able to do it in 10 years' time".

I believe engine efficiency falls above 4000RPM, and drag becomes significant over 60MPH. I've read somewhere that you have to switch off your engine at Swiss toll areas.

I've been told that 80 - 90 Km/h (50 - 55 MPH) is the most economical speed to drive at, regardless of the type of car. The funny thing is, you arrive at you destination (Sydney, from Canberra (approx. 300Km)) only ten minutes or so behind the speedster who roared past you at 140 Km/h.

Paul

Interesting table here showing extra journey times for 55mph versus 65 mph

Drive55.org

I get great MPG from my motorbike at 80mph, don't see what all the fuss is about.

Maybe you should try weetabix

Eat the box instead, there are more calories in that. Mice do!!

skeptik wrote: Other suggestions... engines which automatically switch off when a car is stationary for more than a few seconds.. I think I read that this is now obligatory for cars sold in Switzerland (dont quote me)

My Rover Mini used to do that before I got the idle speed adjusted. Never thought of it as a benefit though!