Why Don't Road Cars Have In Screen Front Demisters

[Falchoon]

The V8 Supercars have a built in front windscreen demister (like the rear window but in the front :hiwelcome: ) so why do road cars persist with this ancient technology of blowing air on the screen to demist. Sure it would be a little distracting at first until you got used to it, no more so (probably less) than fluffy dice and all the other crap you see hanging off some people's mirrors. What are other people's thoughts on this subject?

[KEN 24T]

Are you saying that you would have demister wires running parallel in the windscreen like you do in the back window?

If so, I think this would be very difficult to get used to.

Not sure I'd go for this.

2.2c

[aaronmihe]

I think it's in part due to laminated screens not liking to the two different glass sheets being at different temps 'suddenly' with hotspots. Would proabbly destroy the poly-inner bonding layer.

Then we have the distraction issue.

[Velvet Glove]

Have often thought about the same question. I just assumed someone smarter than me had a reason

[Trumpy]

I find that the front screen unfogs almost instantly when you press the button for front demist (ie A/C goes on, air directed to screen), whereas the rear takes a while for the demister bars to heat up. Plus you get the fog 'lines' as it gradually heats the area between the demister lines.

Safety wise, I'd rather use the A/C system to unfog the front.

Perhaps the reason the race cars use it is because they dont retain the ventilation/AC system used on the road cars.

[Macktheknife]

Trumpy is bloody dead right.

Nothing is faster for demisting than a combination of heater/air con.

That's what is employed as soon as you hit the demist button in the all new cars.

Why is it so good?

Because the action of cooling the air with refrigeration instantly de-humidifies the air resulting in a much increased ability to again absorb moisture. Reheating the air again increases this (by decreasing the relative humidity) and also prevents little cold spots from forming on the windscreen.

The reason the V8s use the heated window is because they aint gunna sacrifice reliability and power to run an A/C system.

Mack.......

[ms700]

Touring cars havent always used front demisters. I think it became mandatory after Bathurst one year in the rain, when all the cars were fogging up badly. Ever since then (I think it was the round when the Eggenberger sierra's won then lost) all tourers have had to use them.

[DallasQLD]

The latest Range Rover has a screen demister built in

[BlueXR6Turbo]

  Falchoon said:

Sure it would be a little distracting at first until you got used to it, no more so (probably less) than fluffy dice and all the other crap you see hanging off some people's mirrors.

Most people don't have fluffy dice or other crap hanging from their mirror.

[Guest ADP]

Ford (along with many other manufaturers) has fitting vehicles with heated front screens for about 15 years now. They are a popular option in Europe where they are useful for melting ice and snow off the screen. I suspect the reason Ford does not offer them here is that our conditions aren't generally cold enough. Also if you get a rock through your heated screen it is $$$ to replace.