Up/down or around, which uses least fuel?

ericmark

ericmark

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Llanfair Caereinion, Nr Welshpool
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I live in a Welsh valley, to Welshpool no real steep hills, but Newtown rather steep, but Welshpool to Newtown flat.

A lot more miles around, but mainly cruising, but direct I play tunes with the gearbox, using all high ratio gears.

Winding roads means no run at the hills, but which is cheapest.
 
The latest version of Google maps on my phone highlights the most economical route and give a percentage fuel saving.

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bernardgreen said:
As as rule of thumb the most fuel efficient route will be the route that creates the least heat in the brake pads.
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Not heard of that theory, but it makes a lot of sense. Perhaps people that drive at excessively low speed as a fuel saving exercise, but also constantly brake, should be made aware ;)
 
norseman said:
Not heard of that theory, but it makes a lot of sense. Perhaps people that drive at excessively low speed as a fuel saving exercise, but also constantly brake, should be made aware ;)
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Best economy is a compromise between speed and wind resistance, using a low throttle opening, plus a the highest gear. A steady speed, is better than a variable speed.
 
Does your car have a trip computer? Might be worth zeroing it and trying each way a few times and averaging the results for each route? They're not especially accurate in absolute numbers (unless your car is very new) but they should be good enough for back-to-back comparisons?
 
norseman said:
Not heard of that theory, but it makes a lot of sense. Perhaps people that drive at excessively low speed as a fuel saving exercise, but also constantly brake, should be made aware ;)
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Back in the 60s and 70s the older Saab models (95 and 96) had freewheel gearboxes to improve fuel consumption. I drove a 95 estare for work for a short while. Frightened the bejayzus out of me on the first steep downhill stretchp in the Pennines (zero engine breaking, obviously). Talking of which I was taught to be light on the brakes, and to use engine breaking. It certainly makes sense in a country like Scotland in winter
 
JobAndKnock said:
Back in the 60s and 70s the older Saab models (95 and 96) had freewheel gearboxes to improve fuel consumption. I drove a 95 estare for work for a short while. Frightened the bejayzus out of me on the first steep downhill stretchp in the Pennines (zero engine breaking, obviously). Talking of which I was taught to be light on the brakes, and to use engine breaking. It certainly makes sense in a country like Scotland in winter
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Were they the 2-stroke Saabs?
 
Nope. I'm not that old! They were the ones with the Taunus V-4 engines. The 2-stroke designs were dropped from around 1967
 
I go to wales only to burn some fuel on low gears around the bends.
After 10 minutes of driving I could light a cigarette on the brake discs ;)
 
JobAndKnock said:
Nope. I'm not that old! They were the ones with the Taunus V-4 engines. The 2-stroke designs were dropped from around 1967
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Ah OK. I was in Berlin the other week and of course, among other things, they had a load of Trabant stuff. They too, had the free-wheel on over-run, but I learned something interesting (to me, at least)! I had always assumed it was a fuel-saving thing, but apparently, it was an engine-saving thing. With a 2-stroke being lubricated by oil that gets sucked in with the fuel, if you use the engine as a brake, with the throttle shut, it starves it of lubrication!
 
Avocet said:
Ah OK. I was in Berlin the other week and of course, among other things, they had a load of Trabant stuff. They too, had the free-wheel on over-run, but I learned something interesting (to me, at least)! I had always assumed it was a fuel-saving thing, but apparently, it was an engine-saving thing. With a 2-stroke being lubricated by oil that gets sucked in with the fuel, if you use the engine as a brake, with the throttle shut, it starves it of lubrication!
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The other thing with two strokes, was the advice not to run them flat out/wide open for too long. You were supposed to dip the throttle often, to allow the oil to be splashed up the bores.
 
Harry Bloomfield said:
The other thing with two strokes, was the advice not to run them flat out/wide open for too long. You were supposed to dip the throttle often, to allow the oil to be splashed up the bores.
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Interesting, I wasn't aware of that? Obviously my strimmer and chainsaw, by their nature, can't over-run and get their throttles dipped quite frequently, but I have an outboard motor which (as far as I'm aware) is supposed to run for hours at a time at constant throttle? (Mind you, the piston is on its side, so maybe the "up" the bores concept goes out of the window)?
 
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