Driving Economically - 56mph Myth??

MickKnipfler

Just get a 3 cylinder diesel Hyundai Getz and rev the b0ll0x off it! 80mph 80mpg, easy!

SeriouslyStressed

just buy an economical scooter :rotfl: something around the 100mpg mark:D

110frankie

I'm happy enough with my Range Rover with LPG.
Cost to buy £1500
cost to run 36p a litre

now that's an MSE vehicle !

SeriouslyStressed

ah.. range rover.. but you dont mention the actual costs...of running...

tyres, brake pads, disc's, spark plugs, bearings, oil, filters, exhaust, suspension parts etc, etc... it'll all be to buy at some point along the way as is insurance, tax, mot fee etc...

these are the hidden costs.

Generally, the older the vehicle, the more it will need doing to it.
It is negligent to leave something that needs doing until MOT time as it might be that the vehicle is unroadworthy/unsafe in the meantime.

Having said all that... LPG seems a great option if you have LPG stockists on your regular routes out and about.

kittiwoz

Seriously_Stressed wrote:

Generally, the older the vehicle, the more it will need doing to it

Not exactly. The failure probability density curve for a car, as with many things, is bathtub shaped. This means there is an initial period whith a high probability of failure (refered to as infant mortality) which gradually levels out (typically by three years). This is what warranties are designed to cover. Then there is a long period where the probability of failure is constant which lasts up til about 100,000 miles. Failures in this period will be largely consumables. After that the probability of failure will increase as the vehicle nears end of life. Between three years and 100,000 miles the relaibility is the same. However obviously the older the car is the sooner it will reach 100,000 miles and start to need more work.

tomstickland

I've only been under 100K in any of my cars for a few months; in 10 years I've probably spent 98% of my time with +100K cars. I've got a 178K BMW at the moment and spend virtually nothing on it.

kittiwoz

Well that's supposed to describe a typical curve but I don't know how old the figures it is based on are and it does vary between types of car. I'd expect a BMW to last well because they are known for solid build.

My dad normally has cars that have done over 100,000 miles, many of them have been older than I am (24). While he spends less on them than many people with much newer cars because he does his own maintenance he does put quite a bit of time into them. Whether around 100,000 miles or later cars certainly do reach a point where they become less reliable.

But really my point was that there is a long period of time where the reliability is constant and almost all the things mentioned by SeriouslyStressed are consumables so the likelihood of them needsing replacement is largely not dependent on the age of the vehicle. So it is not true to say that, generally, the older the vehicle, the more it will need doing to it and in fact a car that is, say, 5 years old will normally be more reliable than the same car was when 6 months old.

wolvoman

Back on topic I was playing about with the trip computer in my car last weekend at night so the motorway was very quiet and I wasn't holding anyone up.
I'd reset the trip computer and drive for 1 mile at each of several speeds and note the average mpg over that mile. The speeds are all GPS speeds (I have a gadget fitted to the car).

45mph - 43.7 mpg
48mph - 43.9 mpg
50mph - 45.7 mpg
53mph - 46.3 mpg
55mph - 47.9 mpg
58mph - 49.0 mpg
60mph - 48.8 mpg
63mph - 48.0 mpg
65mph - 46.0 mpg
70mph - 41.3 mpg
80mph - 33.0 mpg
90mph - 26.5 mpg
Won't go any higher!

Unscientific I know but it shows a pattern.
This was in a 3.2 litre Porsche so not the most economical example.

tomstickland

My dad normally has cars that have done over 100,000 miles, many of them have been older than I am (24). While he spends less on them than many people with much newer cars because he does his own maintenance he does put quite a bit of time into them. Whether around 100,000 miles or later cars certainly do reach a point where they become less reliable.

I reckon it's about 200K that a car is getting to the point of excess wear.

Madiba_2

The most economical speed for any car is its maximum speed with no gas.