Privacy Glass in cars

Personally, I'm an excellent driver but I'm amazed how many accidents I see in my rear view mirror!

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Long time ago, when I did the ROSPA advanced driving course, the easy answer to that was “Two Seconds”

… There was even a ‘mantra’ at the time: Intended to drum it Into people:

”Only a fool breaks the two-second rule”

Do the sums, and you will see close correspondence with the multitude of “stopping distances”

… it still works for me [except, of course, when somebody dives into that massive gap]

MichaelG.

As a significant number of us are probably old gits we have probably discovered that the accelerator is a proportional device and not a switch and our copilot prefers smooth acceleration and gentle braking. We have probably discovered that going hell for leather gains only a few minutes on a journey time but wears our vehicle out and drains the tank very quickly. My wife’s cousin lived just outside Paris for a few years and remarked that he had learned to drive his car properly on his trips to visit his parents in West Oxfordshire, he was having to stop for fuel when he made the trip with aggressive throttle and hard braking but he could comfortably make the trip on a tankful with a more economical driving style. I think his rear windows were clear.

Mike

When I can't see through the vehicle in front, I do pull back a shade. Vans, lorries, caravans and buses make it advisable to drop back a bit; they all make it difficult to see trouble ahead - such as a car in front of them doing an emergency stop.

It's about time rather than distance. Human reaction time varies from about 100mS to 500mS or more. It gets slower with age, so beware pensioners who imagine they have the same reactions they had as a teenager; they don't. Interestingly, the fastest reaction times are achieved by boys in their early teens, and it's not maintained after age 20. After about 35, the deterioration becomes marked, and it's one of the fitness issues that finishes sporting careers.

Anyway, assuming the driver reacts within 333ms, and is in a line travelling at 30 metres per second (nearly 70mph), how much is notice is needed to stop safely?

333mS is 10 metres, so that's too close - the driver hits the brakes at the moment he ploughs into the wreck. In this time-frame the driver doesn't alter the outcome at all. His fate depends on how much energy is absorbed by the vehicle crumpling, how fast the airbag deploys, how effective the seat belt is in an extreme collision, and if the vehicle is struck by whatever is behind. Being seriously rear-ended is more likely if tinted windows prevent the driver behind reacting quickly.

666mS is 20 metres, which is still too close. Nothing happens for 10 metres and then the brakes go on. They have to stop the vehicle within 10metres, which is unlikely even if the tyres don't skid and the driver applies them optimally, and he doesn't have time to think.

A full second gives the vehicle 30 metres of stopping space, which is much better. Even so, the probability is the car will still be doing 20 or 30mph at impact. Although the driver might still end up in a meat sandwich due to being rear-ended, his chances of escaping serious injury are good.

Allowing two full seconds gives 60 metres of stopping space, which seems to prevent most accidents, especially as dead-stop emergencies are rare. We usually get more time to react.

I was taught to leave a 4 second gap between me and the vehicle in front. An over-cautious allowance when I was young, it makes more sense now my concentration isn't so good. Anyone else find driving at night unusually tiring? If so, allow a bigger gap. Same if distracted. Having a row with the wife, getting lost, dying for a pee, drunk, ill, tired, using a hone, or being unwell all play havoc with reaction times.

Statistically half of those reading this post are below average drivers. Anyone apart from me prepared to admit it? All my friends and colleagues consider themselves good drivers, including one who totted up enough points to be disqualified, and another who spent 3 months in hospital recovering from 'polytrauma' after a head-on crash due to him doing 80mph on the wrong side of the road.

Though I'd describe tinted windows as 'mostly harmless', I don't see much need for them apart from undertakers Private Ambulances. I suppose others might see them as a mildly anti-social selfish affectation, probably driven by a big-headed numpty proclaiming he's "special". Tinted glass wouldn't stop me buying a decent second-hand car though.

Dave

Edited By SillyOldDuffer on 13/12/2022 10:11:07

It continues to amaze me how many (typically but not always younger drivers) have yet to work out the relationship between accelerator, brakes and tyre wear.

I also did the ROSPA advanced driving training (and managed a silver on 1st attempt at the test which I was very pleased at)

I can thoroughly recommend doing it, (you use your car and fuel) but the instructors give their time for free.

My instructor was a retired police advanced instructor and I certainly learnt a lot from that guy, and now drive to a much higher standard, but I certainly don't dawdle !!

My ability to 'read the road and predict what the other guy is doing' is much sharper than before, also my car mpg has improved and tyre wear is also much better.

Almost all new premium cars (Mercedes, Audi, BMW etc) have factory fitted tinted rear glass.

I have a MB estate, and all glass rear of the 'B' post is very dark.

• it provides security for any thing in the back
• cooler inside in hot weather
• looks really nice with the cars satin black trims
• was OEM so I didn't have a choice

From the inside it is almost indistinguishable from clear glass and does not hinder rear mirror vision, also rear passengers view is not compromised in any way.

As well as the 2 second rule, the another mantra taught on advanced course is that you should always be able to stop in the distance that you can see to be clear.

Hi, in the highway code, the typical stopping distance at 70 MPH is 96 meters, that being the length of 24 cars at an average of 4 meters per car. At 70 MPH you are traveling at about 31.3 meters / second, so that typical stopping distance at 70 MPH would take you about 3 seconds, however once you start to brake, which is after about 21 Meters, your speed will reduce very quickly, so your stopping distance should be within the 2 second gap rule, but this is with the vehicle, the road conditions and the weather all being in good favour. and with wet roads the gap should be doubled to 4 seconds and much more on icy roads. Other drivers will jump into a wide gap and the only thing you can do is slow down until you restore the safe gap. A two second gap at 70 MPH will be about 62.5 meters between you and the car in front, but if the car in front starts to do a bit of speeding, your gap should get bigger and bigger, so you should always keep an eye on your own speed.

The photo below shows a section of the M62 where there are chevrons that guide you to have at least two of these between you and the vehicle in front, these are at a distance of 40 meters apart giving you a gap of about 2.5 seconds, but of course larger vehicles should have a bigger gap anyway in good conditions let alone bad ones, I was a passenger in this 3.5 Tonne Peugeot van on a bit of a damp day, but I don't think we were traveling at 70 MPH at this point, although I did think we were a bit too close to the vehicle in front, but that lorry on the left was clearly a bit too close to the vehicle in front of it, as there was not even one chevron in view between them. I think the driver of our vehicle slowed up a bit to increase the gap, when I said he didn't have a two chevron gap, as we had quite a bit of heavy gear in the back of the van.

Regards Nick.

Many people have claimed that security glass is more secure for anything left in the back, but is their empirical evidence for this or is it just a salesman's sale gimmick? My gut feeling would be the opposite, vans often have signs saying no tools left inside feeling that they are vulnerable from attack. Wouldn't criminals be more likely to break into a more expensive looking car on the offchance of it having something expensive inside? I always leave valuables in the boot, but as there seems to be a general believe that its ok to leave things in the back of a blacked out car, if I was a criminal these would be my target.

Whilst I do not leave items in plain view, I would break in to a car with items on display, easier pickings.

Ian

I don't think there is a general belief that it's OK to leave valuables in the back of a car with tinted windows, and that's what they are 'tinted' not blacked out. However, anyone can forget they left something for whatever reason, and the lack of visibility from the outside is a bonus. I really don't get the point of this thread. These windows are not just on the expensive brands, so it can't be the usual jealousy.

Exactly, it's just another pointless "Victor Meldrew" thread, highlighting and complaining of problems that don't really exist.

The police advice seems to be don’t leave items on display in your vehicle, as criminals usually don’t bother smashing into cars just on spec then I expect they don’t bother if nothing can be seen, if they took the approach that privacy glass must be hiding something then they would be very busy with little reward. I would always put a laptop or similar high value portable item in the boot but as my jacket will be just a jacket with no phone or wallet then I will risk it in the footwell with dark windows, I doubt there is much demand for a second hand jacket for a fat bloke.

Mike

Lorries will leave their back door or curtain sides open when parked up empty, to stop criminal damage to an empty lorry. Vans often need to security of extra door locks. If all a criminal can see is empty cars or blacked out cars doesn't it make it more likely that they might be broken into? Just curious if their is evidence either way?

You've all missed the point completely.

Privacy glass is fitted so that the little darlings don't have to suffer the traumatic social stigma of being seen by their peers, travelling in a Ford Fiesta. That is why it is a standard fit on the type.

The only thing I watch for, through the vehicle in front, is the brake lights or indicators of the ones further forward. I don't find privacy glass obscures them significantly especially if the car in front is driving so close to the one in front of them that I can't see the lights directly. Cyclists, pedestrians, deer, pheasants etc I infer from the deviations (swerves!) of the vehicles further forward, and I see them down the outside of the one in front.

It depends what the measure of a good driver is, I shall not be troubling Lewis Hamilton on a gp track but I hope my roadcraft and patience will keep me out of trouble. I always said if you can survive until you are 25 on a motorcycle you may be in with a chance of making a safe motorcyclist but that got turned around by middle aged gents buying fireblades and R1s and killing themselves, a bit more of a handful than old Bonnies and commandos which were probably the last thing they rode. Is this guy insane, a brilliant rider or just luckyGhost Rider 2022

Mike

Most people seem incapable of leaving a safe distance in front of themselves, when they see someone driving a safe distance they assume you've left space for them to cut in, bring on semi autonomous vehicles that have sensors blocking drivers from cutting in where there isn't space or driving too close to the car in front.

I'm indifferent on tinted windows, my car has them but only because the previous owner had it done, rear 3 windows on a hatchback done in a very dark tint and front light, it does hinder the ability to reverse at night time, I wouldn't bother doing it myself but it's already there so I just leave it, I must admit I do like the privacy in slow moving traffic but earlier today while driving I did think about what people had said and maybe there is a point to be said about seeing the car in front of the car fronts brake lights, but only in slow moving traffic.

When actually driving I tried looking through through the car in fronts windscreen driving at 40mph about 20 car lengths behind them which is what I deemed safe for that road at that time, and my vision isn't good enough to see anything of value from that distance through their window, the approach I generally use is as you say just gently put the brakes on to put a bit of distance between my car and the car in front, then continue at your previous speed.

I parked up near the city centre of Leicester last year and witnessed two men brazenly walking car to car putting their face to a car window with their hands cupped around their eyes to see better, they were walking car to car without a care in the world so I believe they do look for something to steal before smashing your window, not living in an area like that is probably a much better option than tinted windows.