Building a Raspberry Pi GPS Speedometer

edit: I just noticed the multi-meter glued to the "dash". Nice.

First off, check out the front bumper. Bull bars like that were banned in the UK and throughout Europe on grounds of safety. This wasn't a recent ban either. The bull bar says a lot about what the driver thinks of other people and, in this case, through the lens of a EU citizen, it is not friendly.

Then there is the general safety aspect of the design of this vehicle. It is the worst hotch-potch of compromised design you could come up with. It is in Homer Simpson territory. The problem was the rollover test, so they lowered the tyre pressures and thinned out the material in the roof to give it a lower centre of gravity. So if you did go round a corner (like they have in European roads) then you could end up crushed to death. But let's not be self-centred, due to the bulk of the vehicle you could also crush the occupants of another vehicle to death. Not a good look.

The eventuality of this is rare, but more likely if the speedometer has been mangled into some Raspberry Pi screen. Try explaining that to the police, insurance company and grieving family members.

The low tyre pressures and the general obesity of the vehicle meant that fuel economy was worst-in-class. This vehicle is therefore the worst type of gas-guzzler, the poster-child-SUV for global warming. They sold these excuses for vehicles as 'trucks' rather than 'cars' as it was a tax fiddle that, combined with the 'Chicken Tax', meant that lousy design was permitted. So much for the 'free market' and 'competition'.

I would say the hacky Raspberry Pi speedometer is well suited to the general hackiness of the vehicle's botched and very American engineering. It is in character, a quick and dirty solution that certainly would not meet EU standards for safety.

A proper mechanic would rip this hacky solution out and put in the correct cable/sensor in minutes. Sometimes you have got to respect the skills people have and wonder why it is they do it properly rather than go for abominable hacks. But this vehicle isn't worthy of a mechanic's time, it needs to be taken out to the scrapyard and replaced with something practical like a planet-friendly bicycle.

Regulation 35 does allow compliance with alternative requirement, either Community Directive 75/443 or with ECE Regulation 39. These I am not familiar with, but the Regulation 36 regarding maintenance states:

"Every instrument for indicating speed fitted to a motor vehicle shall be kept free from any obstruction which might prevent its being easily read and shall at all material times be maintained in good working order."

Therefore, the original one would need to be removed to even begin to be legal.

I wonder if you could use something like this [0] and feed info from the pi over OBD using some sort of OBDII breakout board or OBDII <-> USB device.

[0] https://www.aliexpress.com/item/32966911948.html

I did a lot of soldering as a microwave tech, and used a setup like that just for convenience. I have to have a magnifying glass on a similar flex arm because my eyes are so bad. I suppose there are still some hard parts, like trying to use braid to remove solder, but I bet you can do it.

I have a 1991 Mitsubishi Galant VR4 that has a place in my heart that your Subaru seems to have. Cool family compact with 4WD and 500 oversized, at the wheels, turbo HP.

Even if that works, doing sensor fusion with a gyroscope and an accelerometer probably is both easier and cheaper.

While you can calculate based on position fixes, it is more accurate for the GPS to do it. It does not do a simple distance/time calculation but can instead look at the phase / doppler shift of the GPS signals. This ends up being much more accurate.

I am not sure what you can get away with for DIY replacements - perhaps a police officer might give you the benefit of the doubt if you were polite and explained it was temporary while you are waiting for the real part, but I really suspect this would force your car off of the road at the next annual safety check/inspection (MOT test in the UK)

Basically, if your car came with a safety feature, it has to still be there and it has to work. Car had no ABS when new? Doesn't need it. But if it had it, then it has to operate.

As for rust, it needs to be close to structural points in order for your car to fail a WOF. If you have rust near a pillar or on your firewall, there's a good chance it's worse than it looks and a safety hazard. Rust is a cancer for cars, it might not look bad at first, but it will eat your car from the inside out.

Your car basically just has to be safe, that's what your WOF is for. You can modify your car to your hearts content, you just need to get an engineer to sign off on it to say it's safe. Want to stuck a RB25DET in your old ute? No worries, just get a cert.

Then you come to Australia, where each state has a plethora of "anti-hoon" laws, banning you from having both a pod filter and a straight pipe, and other arbitrary rules to stop you from modifying your car. It's ridiculous and also inconsistently enforced, nobody seems to know what the actual rules are here.

There is a good reason this is illegal in most of the world. Not sure why you don't put car safety as a priority? 40,000 people die every year in the US, and over 4 million are seriously injured.