Can I use GPS unit instead of the car's speedometer?

When I broke my speedo cable earlier in the year I drove around without one for ages. While I used a gps a few times out of curiosity and nerdish curiosity, I think I mostly just went with the traffic flow and erred on the slow side to be safe. It took a few days to get used to not having the speedo to look at, but when I did (get used to it) I enjoyed driving more. I think banning speedos from all cars would actually make roads safer.

As for that ridiculous anchor example….. Obvoiusly you would need two. On each side for turning corners and both together in order to stop.

justsomeaussie said :

Contrary to the people guessing on here. You’ll find that GPS will give you a more accurate reading of your speed than your speedometer. Speedometer’s are traditionally calibrated to be 8km under what your actual speed is. It’s to give you the perspection of driving faster than you are. GPS on the other hand can give a much closer approximation of your real speed over enough distance. Also noting that GPS has an error of 6-10m.

I believe everything I read on the internet. Except for this.

You can’t seriously think that assisted gps can beat a mechanical system in terms of accuracy? There are a lot of things that can mess with the signal, as anyone who has ever used a damned smartphone would know. The time to receive, then to calculate the position and render it alone would create a lag. Because the iPhone/smartphones are not designed to be used in lieu of a speedo, their quality of service will differ greatly. For example, in the event of a major disaster, weather event or holiday the tower speed could degrade. The smartphones do not typically make a display of current latency, cell handovers and so forth so the driver would have no idea that they’re being fed bad data.

The OP said something about just following other drivers. My previous car had a very accurate speedo. Canberra drivers do NOT typically drive anywhere near the limit. When I took my test, my instructor made it clear that I was to go at, and sit on, the speed limit. I imagine any competent instructor when told “I cant verify my speed” would just scratch the test right there.
We certainly learn over our lifetimes how our vehicles perform. Do you really think an L plater has driven her auto so much that she not only knows which gear its in, but can accurately figure out her speed via tacho on varying slopes?
If OP is for real, she needs to hire a car or a get a loaner from a friend.

Contrary to the people guessing on here. You’ll find that GPS will give you a more accurate reading of your speed than your speedometer. Speedometer’s are traditionally calibrated to be 8km under what your actual speed is. It’s to give you the perspection of driving faster than you are. GPS on the other hand can give a much closer approximation of your real speed over enough distance. Also noting that GPS has an error of 6-10m.

That all said. As said above, you still need a speedo to have a roadworthy car.

Henry82 said :

Jesus, i can’t believe it. Yes its an instant fail. The car must be roadworthy.

As posted by sarahsarah, the following applies:

1.43 Speedometers
(1) A motor vehicle (other than a trailer) built after June 1974 that can be driven faster than 50km/h on a level road must be fitted with a
speedometer.
(2) The speedometer must—
(a) indicate the speed at which the vehicle is being driven in
kilometres per hour; and
(b) indicate, when the vehicle is travelling faster than 40km/h, a speed that is not over 10% less than the actual speed; and
(c) be readily visible to the driver.

I’m not convinced that a GPS fails that criteria. Would be interested to hear if anyone’s gotten away with it!

Henry82 said :

GPS’ are not accurate, if you go through a tunnel, the signal is blocked, you go on curvy roads etc etc you will not get an accurate indication of speed. Oh and its not instantaneous either.

Sounds like you’ve never driven with a GPS.

An analog speedo isn’t instantaneous either! GPSes
– typically update once per second and may be averaged over several seconds, which is sufficient for driving purposes.
– are far more accurate than the average analog speedo
– are unaffected by changes in tyre wear, air pressure, etc.
– accuracy is not affected by curvy roads.
– could make use of accelerometers to update speed when signal is lost (but I couldn’t name a model that does..)

Henry82 said :

grdem said :

Also, if you know which gear the car is in and can read the revs on the tachometer, you can get a pretty good gauge of speed.

Revvs isn’t displayed in km/hr, and it isn’t “accurate”

Just as accurate as an analog speedo. Anyone with a tacho in their manual car will sooner or later have figured out the ratio of each gear, and thus know their speed from the revs. (3000rpm in 4th = 82kmh, etc)

Solidarity said :

Are you sure? I would have thought that being the judge of road-worthiness is not something the intructor would be too keen about, considering it’s not thier job. They’re an instructor, not a roadworthy inspector.

They need to be safe in the car, i wouldn’t want to get into a car i know is unroadworthy. Particularly with someone who hasn’t actually passed their driving test yet. It doesn’t take a mechanic to look at a car, and realise its unroadworthy. Sure theres stuff under the bonet, but anyone can do a basic pre-inspection and be 95% sure the vehicle is in a roadworthy condition.

Solidarity said :

Are you sure? I would have thought that being the judge of roadworthiness is not something the intructor would be too keen about, considering it’s not thier job. They’re an instructor, not a roadworthy inspector.

Whilst I’m pretty sure that OH&S guidelines would require a driving instructor to do a quick check over of the car and anything obviously wrong would prevent the instructor from hoping into the car, maybe a driving instructor \ examiner could jump on and advise if checking that a car is in their opinion safe to drive a deal breaker when it comes to getting a license?

I’m sorry, but the fact you even ask this question indicates you were issued your permit in error and should have your “L”s taken from you until you learn the rules of the road.

I’ve always thought the testing regimen that leads to people being licensed to drive on our roads is incredibly lax, and here is proof. The roads are absolutely chockablock full of people who are dangerously clueless, and that’s about to become chockablock+1.

harvyk1 said :

grdem said :

Original poster here…

Most of the time I’m pretty much the only one on Canberra roads who isn’t speeding.

Without an accurate speedo how can you be sure?

That post was full of WIN!!

harvyk1 said :

Solidarity said :

harvyk1 said :

grdem said :

Original poster here…

Most of the time I’m pretty much the only one on Canberra roads who isn’t speeding.

Without an accurate speedo how can you be sure?

Could you tell the difference between an engine running at 2000rpm and 2500 rpm instantly?

Errr, look at the tacho?

Well he did state that “listening to the engine” forms part of his driving without a speedo strategy. For him to be so high and mighty on “I never speed” he would either need to drive many km/h under the speed limit or know his diff ratios and be really excellent at maths on the fly.

But of course this is all beside’s the point. Even if you don’t agree that a speedo is an important part of a car, or makes it unroadworthy if a car does not have a working one, someone other than you or I have decided that it is required, and they also had the power to enforce it, and in this context a driving instructor will not pass someone in a car which is unroadworthy.

Are you sure? I would have thought that being the judge of roadworthiness is not something the intructor would be too keen about, considering it’s not thier job. They’re an instructor, not a roadworthy inspector.

Then again i’ve had cars defected on the side of the road, only to be passed by Dickson without me doing anything to them. Pain in the arse because then you need to wait at Canberra Connect for hours.

Lazy I said :

using a boat anchor to brake

My advice is to ask the instructor to ‘nurse’ the anchor, and then hoik it out the window at your request. If you fail to slow in time and rear-end someone, you can give them the accusing eye.

And speaking from experience, just be aware that the car can come to a very abrupt stop, so make sure you use seat belts. Also ask them to avoid throwing out the anchor too far way from the car. Sometimes it hooks onto a pole or something and next thing you know you’ve done a full U-turn without indicating onto the footpath. It’s one of the main reasons people fail driving tests when using anchors for brakes. So be ready with the indicator just in case. Good luck.

Solidarity said :

harvyk1 said :

grdem said :

Original poster here…

Most of the time I’m pretty much the only one on Canberra roads who isn’t speeding.

Without an accurate speedo how can you be sure?

Could you tell the difference between an engine running at 2000rpm and 2500 rpm instantly?

Errr, look at the tacho?

Well he did state that “listening to the engine” forms part of his driving without a speedo strategy. For him to be so high and mighty on “I never speed” he would either need to drive many km/h under the speed limit or know his diff ratios and be really excellent at maths on the fly.

But of course this is all beside’s the point. Even if you don’t agree that a speedo is an important part of a car, or makes it unroadworthy if a car does not have a working one, someone other than you or I have decided that it is required, and they also had the power to enforce it, and in this context a driving instructor will not pass someone in a car which is unroadworthy.

harvyk1 said :

grdem said :

Original poster here…

Most of the time I’m pretty much the only one on Canberra roads who isn’t speeding.

Without an accurate speedo how can you be sure?

Could you tell the difference between an engine running at 2000rpm and 2500 rpm instantly?

Errr, look at the tacho?

Lazy I said :

My car has no brakes and I don’t want to replace them because brakes are expensive. My partner gave me a boat anchor and has shown me how to correctly deploy it out the passenger side window when I am approaching a corner in order to slow the car down enough to take the corner.

most of the test will be on the highway, use the crash barriers on the side to slow you car down. Good luck!

grdem said :

Original poster here…

Most of the time I’m pretty much the only one on Canberra roads who isn’t speeding.

Without an accurate speedo how can you be sure?

Could you tell the difference between an engine running at 2000rpm and 2500 rpm instantly? Because in my car that’s the difference between doing 100km/h and doing 115km/h in 6th… One of those speeds I keep my license, the other becomes expensive. Don’t forget you then have road noise, drive train noise and other noises which start drowning out engine noises (not to mention the radio) the subtle difference between 2000 and 2500rpm become much harder to [b]accurately[/b] tell whilst also controlling a ton of metal.

Lazy I said :

Hi all, I have a quick question about taking my P plate test, it is somewhat related to the original poster’s request.

My car has no brakes and I don’t want to replace them because brakes are expensive. My partner gave me a boat anchor and has shown me how to correctly deploy it out the passenger side window when I am approaching a corner in order to slow the car down enough to take the corner.

My question is, when I am having my final test, is the instructor required to sit in the passenger seat? I am concerned that having someone sitting in the passenger seat may obstruct my access to the boat anchor and compromise the safe operation of my vehicle.

Is it possible to ask the instructor to sit in the back seat for the duration of the test?

Thanks everyone!

Use the clutch and gearbox to slow down, and the handbrake to stop. Don’t tailgate anyone.

Jesus, i can’t believe it. Yes its an instant fail. The car must be roadworthy. You won’t even leave the carpark if they catch it. GPS’ are not accurate, if you go through a tunnel, the signal is blocked, you go on curvy roads etc etc you will not get an accurate indication of speed. Oh and its not instantaneous either.

arb said :

(if) you can’t adapt to driving a different car (…), then you are not ready to hold a license. Simple as that.

I completely agree.

grdem said :

Also, if you know which gear the car is in and can read the revs on the tachometer, you can get a pretty good gauge of speed.

Revvs isn’t displayed in km/hr, and it isn’t “accurate”

grdem said :

That and using common sense and not going faster than other cars on the road makes me certain I’m not speeding. Most of the time I’m pretty much the only one on Canberra roads who isn’t speeding.

That isn’t an accurate indication of speed either. There’s a slim chance you’ll get away with it, and if you’re caught, you’ll lose your money, plus they won’t be able to take the test for a while. Find a friend, borrow a car, hire a car (instructors do this for learners). The whole thing seems silly, next time you get the car checked, the mechanic will fail it anyway.

Dear everyone on RiotAct,

Please do not feed the trolls.

Regards,
luther_bendross

Solidarity said :

Classified said :

Solidarity said :

Keijidosha said :

A broken speedo is no worse than having bald tyres, broken wipers or no lights. The car still drives okay so why is it a roadworthy issue?

I think a better comparison would be “having a broken speedo is like having a broken radio, broken air conditioning or broken cruise control”, as it doesn’t impede the actual functionality (in all conditions) of the car itself.

Nor do the items in my example, under the right conditions.

Note the words in brackets.

I’ll concede that sensible, skilled drivers could probably drive around with no speedo and never have an issue. The problem is that a lot of drivers are neither sensible nor skilled.

Original poster here…

“If at the time of going for your provisional license, you can’t adapt to driving a different car and are therefore worried you’ll fail the test in a borrowed/hired car (especially an automatic), then you are not ready to hold a license. Simple as that.”

I’m as likely to pass the test in any other car as in my little auto – but if it was possible to use a GPS speedometer, then why pay to hire a different car?

Also, if you know which gear the car is in and can read the revs on the tachometer, you can get a pretty good gauge of speed. That and using common sense and not going faster than other cars on the road makes me certain I’m not speeding. Most of the time I’m pretty much the only one on Canberra roads who isn’t speeding.

Lazy I said :

Hi all, I have a quick question about taking my P plate test, it is somewhat related to the original poster’s request.

My car has no brakes and I don’t want to replace them because brakes are expensive. My partner gave me a boat anchor and has shown me how to correctly deploy it out the passenger side window when I am approaching a corner in order to slow the car down enough to take the corner.

My question is, when I am having my final test, is the instructor required to sit in the passenger seat? I am concerned that having someone sitting in the passenger seat may obstruct my access to the boat anchor and compromise the safe operation of my vehicle.

Is it possible to ask the instructor to sit in the back seat for the duration of the test?

Thanks everyone!

Brilliant!

Classified said :

Solidarity said :

Keijidosha said :

A broken speedo is no worse than having bald tyres, broken wipers or no lights. The car still drives okay so why is it a roadworthy issue?

I think a better comparison would be “having a broken speedo is like having a broken radio, broken air conditioning or broken cruise control”, as it doesn’t impede the actual functionality (in all conditions) of the car itself.

Nor do the items in my example, under the right conditions.

Note the words in brackets.

Solidarity said :

Keijidosha said :

A broken speedo is no worse than having bald tyres, broken wipers or no lights. The car still drives okay so why is it a roadworthy issue?

I think a better comparison would be “having a broken speedo is like having a broken radio, broken air conditioning or broken cruise control”, as it doesn’t impede the actual functionality (in all conditions) of the car itself.

Nor do the items in my example, under the right conditions.

Keijidosha said :

A broken speedo is no worse than having bald tyres, broken wipers or no lights. The car still drives okay so why is it a roadworthy issue?

I think a better comparison would be “having a broken speedo is like having a broken radio, broken air conditioning or broken cruise control”, as it doesn’t impede the actual functionality (in all conditions) of the car itself.

Keijidosha said :

A broken speedo is no worse than having bald tyres, broken wipers or no lights. The car still drives okay so why is it a roadworthy issue?

Bald tyres are fine if the road’s dry, and if there’s no water falling from the sky you won’t need wipers either.

Hi all, I have a quick question about taking my P plate test, it is somewhat related to the original poster’s request.

My car has no brakes and I don’t want to replace them because brakes are expensive. My partner gave me a boat anchor and has shown me how to correctly deploy it out the passenger side window when I am approaching a corner in order to slow the car down enough to take the corner.

My question is, when I am having my final test, is the instructor required to sit in the passenger seat? I am concerned that having someone sitting in the passenger seat may obstruct my access to the boat anchor and compromise the safe operation of my vehicle.

Is it possible to ask the instructor to sit in the back seat for the duration of the test?

Thanks everyone!

A broken speedo is no worse than having bald tyres, broken wipers or no lights. The car still drives okay so why is it a roadworthy issue?

MonarchRepublic said :

Solidarity said :

Does not having a speedo make the car unroadworthy? It’s not like you absolutely need one in order to be able to operate the car safely?

In Victoria it certainly does (page9), for cars manufactured after 1988 at least:
http://www.vicroads.vic.gov.au/NR/rdonlyres/E5F44416-57E4-4164-98F5-69E3E8E1C5E3/0/VSI26.pdf

I would assume the ACT has similar regulations? Hard to tell though, as I can find nothing about roadworthy regulations on the roads ACT website… :/

Yep 🙂

1.43 Speedometers
(1) A motor vehicle (other than a trailer) built after June 1974 that can be driven faster than 50km/h on a level road must be fitted with a
speedometer.
(2) The speedometer must—
(a) indicate the speed at which the vehicle is being driven in
kilometres per hour; and
(b) indicate, when the vehicle is travelling faster than 40km/h, a speed that is not over 10% less than the actual speed; and
(c) be readily visible to the driver.

http://www.legislation.act.gov.au/sl/2000-12/current/pdf/2000-12.pdf

I have a guitar tuning app on my iPhone and it’s hopeless. I’m assuming the speedo one will be hopeless too.

Solidarity said :

Does not having a speedo make the car unroadworthy? It’s not like you absolutely need one in order to be able to operate the car safely?

In Victoria it certainly does (page9), for cars manufactured after 1988 at least:
http://www.vicroads.vic.gov.au/NR/rdonlyres/E5F44416-57E4-4164-98F5-69E3E8E1C5E3/0/VSI26.pdf

I would assume the ACT has similar regulations? Hard to tell though, as I can find nothing about roadworthy regulations on the roads ACT website… :/

Why does it “have to be a gee up?”

If there is other traffic around, follow it.

If not, use discretion to dictate what speed is safe.

It’s not hard.

Solidarity said :

Does not having a speedo make the car unroadworthy? It’s not like you absolutely need one in order to be able to operate the car safely?

This has to be a gee-up.

Solidarity said :

Does not having a speedo make the car unroadworthy? It’s not like you absolutely need one in order to be able to operate the car safely?

I’ve never yet found someone who can accurately estimate their speed under 40kph, which is the speed of some roadworks. Thus, not being able to tell your speed in a 10kph shared zone makes most people unsafe.
Realistically, it’s common sense, which isn’t common because people feel the need to question it.
Cars have to meet certain guidelines to be allowed onto public roads. A speedometer is one of them.

People are just hopeless at figuring what speed they’re driving at with any level of accuracy unless they have one.

Solidarity said :

Does not having a speedo make the car unroadworthy? It’s not like you absolutely need one in order to be able to operate the car safely?

If you consider that driving within the speed limit is an aspect of operating the car safely, then yes, it does.

Does not having a speedo make the car unroadworthy? It’s not like you absolutely need one in order to be able to operate the car safely?

arb said :

If at the time of going for your provisional license, you can’t adapt to driving a different car and are therefore worried you’ll fail the test in a borrowed/hired car (especially an automatic), then you are not ready to hold a license. Simple as that.

This thought also crossed my mind.

If at the time of going for your provisional license, you can’t adapt to driving a different car and are therefore worried you’ll fail the test in a borrowed/hired car (especially an automatic), then you are not ready to hold a license. Simple as that.

nice_enough said :

no sorry… Legally you need a speedometer in the car for it to be considered roadworthy and the GPS system does not replace one.

Driving an unroadworthy car is an instant fail – you won’t even get out of the carpark.

Think about it. What if it’s cloudy?

You “CANT”…Be Serious

Just use it, if you can judge your speed without it, just “neglect” to inform the instructor that it doesn’t work, maybe he’ll be impressed with your… speed judging skills.

Regardless of accuracy, the GPS is not going to give you instantaneous speed.

Thanks for your suggestions everyone. We’d originally intended to hire/borrow a car for the driving test anyway as we’d meant to sell this car months ago (but that got delayed). I’m just really comfortable with this car and would like to use it if possible (it’s an old but zippy little sports hatchback that drives really well).

I guess it depends if the examiner decides that your car is roadworthy or not, but he’s not going to be able to ascertain that until you actually start moving…

If you’d wanted to take advantage of the situation, your best bet would have be to start the test, and quickly say..” Hey, my speedo has just broken. ” Give the examiner some time to digest this and then offer to complete the test with your phone as a speedo.

I’d rather try that then give someone the option of cancelling a test because you’ve admitted that your car isn’t fully functional.

no sorry… Legally you need a speedometer in the car for it to be considered roadworthy and the GPS system does not replace one.

You have a few months to go until your driving test:

Option 1: Get the car fixed.
Option 2: Borrow someone else’s and use the time you have to become familiar with it.
Option 3: Deal with it.