Markybear999
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Was wondering if anyone could advise on how to make the air on switch on the fiat 500 dash any brighter?
Was wondering if anyone could advise on how to make the air on switch on the fiat 500 dash any brighter?
Generally you should never turn the AC off.
the difference in fuel cost between A/C on and A/C off is about 1p/mile; a bit more in summer, a bit less in winter. I use it when I need to, and exercise it at least weekly, but it stays off when it's not doing anything useful. The saving is almost enough to pay for my insurance.
I don't know how much you're paying in insurance but at 1p a mile an average 12,000 mile a year driver is only looking at £120 saving over the course of a year. Even very very cheap insurance policies are not going to be that cheap.
I turn of the radio, lights and air con before switching off the car and don't switch them on until I start it next time (the air con after she's warmed up for a few minutes).
I also don't like starting the car with the A/C on (or anything else for that matter) as the additional load on a stone cold engine is significant (about 2-3kW).
In driving, anything below 30mph it is deemed more efficient to open the windows, anything over 30mph the added drag means it's more efficient to close the windows and turn on the air con.
a low pressure tyre, a slight hill or a head wind are all likely going to make more of a difference than putting the air con on
Main reason to turn the A/C off when not needed is if you've got a non-turbo 4 cylinder car, it will feel like crap at low revs.
Mitsubishi's I-Miev AC is rated for 3kw, or almost the same power it takes for a Fiat 500 to cruise at 30mph. It's potentially a massive hit to economy.
Recent tests have debunked this; current thinking is that running with the A/C on costs you money at any legal speed.
.
1p a mile difference falls in the that category, it would not be possibly to scientifically prove a 1p a mile difference from using the aircon in normal every day use, too many other variables including confirmation bias.
Actually my confirmation bias started the other way - for a long time, I've been trying to refute all those who claim that A/C doesn't significantly impact economy. I'd love to be able to leave it on with a clear conscience.
But I can't.
Cooling a small car using A/C on a summer's day requires at least 10% of the energy that's needed to propel it along at 50-60mph. That's just basic physics; there's no way round it.
I wish that you were right, and I were wrong.
But I'm not.
By the way, last insurance renewal with the 500TA was £154.
Regards to all,
Mick.
............ and I agree with you on the rest too.Yeah I'll concede the insurance point, but stand by the rest
The basic calculation is quite simple.
Petrol has an energy density of about 9.6kWh per litre; a modern engine like the 500 will likely be about 25% efficient, so a 2.4kW A/C compressor running at full power will burn about a litre of fuel each hour.
Now most of the time the compressor will be cycling on & off; if it's working 50% of the time (and 1.2kWh is a reasonable figure for the energy needed to keep a small car cool on a summer's day) then you're buning an extra half litre of fuel an hour. Cruising at 55mph, I'm using a little under 4.5l/hr for propulsion, so that extra half litre an hour broadly agrees with the 10% mpg reduction I've measured over a number of different trips.