Radio or no radio?

[JockoT]

Watched a video about a world record attempt on the Lands End to John O' Groats run in a petrol car. They achieved 94 mpg in a Honda Jazz.
https://www.theaa.com/about-us/newsr...record-attempt
One of the first things they say, after no AC and windows closed, was "and definitely no radio". So just how big an impact does using the radio have on fuel efficiency? I could see a problem if you have a 1200 watt sub woofer and 8 x 100 watt active speakers, but does a normal car radio make that much difference?

[Ecky]

After alternator, battery and equipment efficiency losses, you're probably looking at roughly 2:1 watts in vs watts out. Most aftermarket head units can put out ~50 watts peak, ~20 watts continuous. If we assume 100 watts constant draw at the crank to run the radio, that's about ~15% of 1HP, or maybe 1-2% fuel economy worst-case in most cars.

In my G1 I have a 640w amp and a sub on top of an aftermarket head unit, and generally speaking it disappears into background noise (lol) and I can still hit 90-100mpg blasting the radio. In theory I could be drawing up to 2HP at the crank for maybe a 20% loss in ecnomy, but I'd probably destroy my ears getting anywhere near that. Normal listening volume, even with an amplifier, there's no easily discernible economy loss.

[cowmeat]

In my G1 I have a 640w amp and a sub on top of an aftermarket head unit, and generally speaking it disappears into background noise (lol) and I can still hit 90-100mpg blasting the radio.

What he said.

In my old Insight Turtle I not only had the radio cranked, I also had the rear camera hooked up through the DVD player running all the time and I still averaged over 70 mpg in it. I also averaged way over 70 mpg in Ron Burgundy with the radio blasting and the AC on most days.

In my Volt I always have the radio and AC on (ECO mode), and never notice much of a drop. I don't think the radio draws enough to worry about unless you have a really weak battery or alternator

[JockoT]

I suppose, if you are going for a world record, every little bit helps. I have written elsewhere about my poor highway mileage compared to city driving. The only time I use the radio/iPod is on the highway!

[elhigh]

^^
The thing that strikes me is that I think people are overestimating how many watts their radio pulls during operation. Unless you're cranking the volume until the speakers crackle, it's not as much as all that. I wouldn't guess I'm ever running my radio at more than ten watts' output, thereabouts.

Then again, a lot of the time I'm listening to an audiobook on my personal MP3 player, at which point the issue becomes moot. Headphones and a wearable audio device means no watts at all to the radio except the barest whisper of a fraction of an amp to keep the clock on and retain the memory presets.

[JockoT]

My audio system runs off a 16A fuse. That would, in theory, be up to 192 watts. So allowing headroom, no more than 100 watts. I have only two speakers (the S version for poor people), so a max of 50 watts. It is never played at full lick, so assuming heavy bass, no more than 40 watts. My sidelights use more than that! hardly a heavy load on the alternator.

[cRiPpLe_rOoStEr]

Some people may eventually claim to drive better while listening to some music, but anyway, apart from not having too much impact over the fuel consumption, a portable radio or MP3 player and the phones are usually way lighter than a regular radio.

[vskid3]

I think the difference in mood and concentration from listening to music is the actual issue, not the power draw of the radio. I would bet that I'm a more aggressive driver when blasting music than with the volume low or off.

[cRiPpLe_rOoStEr]

Originally Posted by vskid3

I think the difference in mood and concentration from listening to music is the actual issue, not the power draw of the radio.

Gotta have to agree on that matter, even though the apparently negligible power draw and weight of the radio and the speakers may not be totally disconsidered.

I would bet that I'm a more aggressive driver when blasting music than with the volume low or off.

It might depend on what music you'd be listening.

[JockoT]

They didn't remove the radio for their record attempt. Only switched it off - so the weight didn't come into it. Also, they had an adjudicator in the vehicle. Bet he weighed more than the radio did!