I'm using this in an old 4x4 that we tow behind our RV. The speedo needle is broken on the truck anyway, so this was a good cheap way to get a dedicated speedometer and odometer to track miles driven since the built-in odometer runs even when being towed. This way I can track engine maintenance.
I also wanted to have proof that I'm not going 'WAY TOO FAST'. My passengers always tell me to slow down when we're only doin' 40. Not sure why? Maybe because the truck is 25 years old and basically pieced together from spare parts. Where's the confidence in my mechanical prowess?? You need the shaking to make you feel alive! Anyway. This is a review of a gizmo, not my poor old truck...

This is the first one of this type of unit that I've tried, and it does seem to work okay, the odometer says I've gone about 35 miles since install so more time will tell.
- The GPS lock varies from instant to as long as 1 minute, probably depending on how far the vehicle moved (towed) since it was last driven.
- The 'total driving time', which is the bottom left field, this one I suspect only increments while you're moving. As others have said, a 20 minute drive will invariably read much less if you were sitting still a lot.
- The altitude, as others have mentioned, seems like a waste. It's always there when the vehicle is moving, that field alternates between the time provided by the GPS system and the altitude. I'd rather just have it stay on the time, or possibly alternate between the time and odometer (total miles driven with unit powered on). Also, the time is military (24hr) format, not configurable. If that matters.
- You don't get the odometer display unless you're sitting still, and then that field blinks constantly with the total miles driven.

This unit doesn't have an external antenna, so putting it back under the dash or back under the lip of an instrument cluster might interfere with the GPS lock.

I bought this for my 2012 Mitsubishi Lancer. Sometimes when I'm driving with my hand on the top of the steering wheel it covers my speedometer and I have to keep lifting my hand to see it. For just under $22 I figured it was worth a shot but wasn't expecting miracles for accuracy. It comes nicely packaged in a small box, the unit itself feels pretty light weight. One thing I did have to do is add a small piece of thin gasket material between the mount and the unit because it was a loose fit and I didn't want it bouncing around and falling off while driving down the road. It does come with 3M double sided tape but I removed it and added 3M double sided outdoor tape that is a little more tacky. The problem I ran into was my car was sitting in the garage at night when I put it on my dash and the next morning it had fallen over on my dash. So the next day, which was a hot day, I left it sit on my seat while I was at work. The combination of the hot dash and the tape sitting in the sun seems to have created a better bond and it has not fallen off my dash since.
Now for the technical aspects. It comes with instructions and is very easy to set up. At start up I have never had to wait more than 2-3 minutes for this unit to pick up the signal and that's both sitting and driving while it connects. It comes with a flat cord that has the same connections that an Android device has, but it doesn't come with an A/C adapter for cigarette lighter plugs. I don't have a USB slot in my Lancer so I bought an adapter on Amazon for less than $5. It does have a 2-3 second lag during acceleration and deceleration but once you're at a steady speed it calibrates and adjusts quicker. I did notice that the unit I got seems to run +1 mph more than my speedometer but that's no deal breaker. Overall the unit has a cheap feel to it but I'm impressed with it's accuracy. The screen is bright and clear and easy to read during the day and night. I use it daily for going to work and also on road trips.
*Update* The fatigue alarm that goes off every hour is annoying. I have not found a way to turn it off. If you can remember to power it off and back on before it goes off then it won't beep at you. Cloudy and foggy days seem to throw off the accuracy, it seems to run about +2-3 MPH on those days, but it has to be thick cloud and fog cover.

Bought this for my son so he wasn't stressed out trying to read the dial gauges on the car while learning to drive. This is easy to read, reasonably accurate (it often overestimates by about 1mph, but that's ok), super easy to install and calibrates fairly quickly. If you don't have a 2-outlet usb power plug, get one, and it'll be like it's always been there.

I bought this GPS speedometer/odometer to use in a camper van that will someday have larger than stock wheels, which will make the van speedometer and odometer incorrect. There are a lot of devices that would work except I really wanted one that does not reset when powered down, so it's a relatively accurate reflection of total vehicle mileage. Most of the devices sold on Amazon reset when powered off. This one retains the total mileage. I've only used it for one trip so far. I simply plugged it into the vehicle USB port, set it on the dash, waited until it acquired the GPS signal (display shows a wait cursor while acquiring and shows 0 MPH when acquired) and started driving. It was already set to miles/MPH so I didn't need to do any configuration. It acquired the GPS signal in less than a minute. With the stock tires on the van, the speed and mileage on this GPS device matched the van. I'll reserve the 5th star to see how it works over time but, so far, so good.

I bought the VJOYCAR C60 several weeks ago and am using it in a 2019 vehicle that has a digital Km/h display but not mph. I wanted digital mph also. The GPS speedometer works perfectly. Everything advertised about the unit is true. Set up is no more complex than connecting to USB power. It takes perhaps half a mile to lock onto a satellite and do its housekeeping before speed is displayed. Out of the box it was within +/- 1 to 2 mph.

I did choose to recalibrate the speed slightly. This achieved by pressing and holding the up arrow and enter buttons at the same time. I found that pressing the up arrow just slightly prior to pressing the enter button got me into the calibration subroutine every time.

Another nice feature is upon stopping, such as a traffic signal, the trip mileage followed shortly by trip time in minutes are displayed. Stop signs tend not to be long enough for this feature to activate. Mileage and time are displayed in whole numbers (no decimals), so the longer the trip, the better the data.

Now, there are what appear to be a number of similar devices out there brand labeled by each reseller. The nice thing about the VJOYCAR reseller is that he contacted me personally after my purchase to deal with any issues. I had not noticed that the unit requires a wired USB connection for power, so he kindly supplied a 12 volt adapter so I did not have to sacrifice my USB connector normally used for phone and music.

All in all I am happy with the device. The true test will be our Midwest winter temperatures, but for now I'd buy it again.