ACECAR Digital GPS Speedometer, Universal Car HUD Head Up Display with Speed MPH, Compass Direction, Fatigue Driving Reminder, Overspeed Alarm HD Display Meter, for All Vehicle (G4)

I got this for an antique sports car that has the wrong size tires. Regearing the stock speedometer is not easy So I got this GPS unit. I mounted it on the steering column near the speedometer.Note that the default calibration is to show a number 7 percent too fast. To get the true speed, you have to change the calibration factor to 100.Also, it takes a minute or two to sync up to the satellites each time it is turned on, so be prepared for that when starting each trip.

- Extremely easy to install. Just plug the cable in to the USB/cigarette lighter adapter, start the vehicle, and it starts working!- When I first saw it, the device was smaller than I expected, but the numbers are large enough to easily see, and the device fits well behind my steering wheel.- As mentioned on the Amazon product site, the time is set to Eastern time. The time zone can be changed in settings, but I didn't bother, since all that concerns me with time are the minutes.- I was impressed with how quickly it connects to the satellite without needing internet connection, or a monthly subscription.- The speedometer on my car quit working a couple years ago, so it is great to have this HUD to show me my speed.Attached are copies of the directions (which I could not find anywhere online). I did decide to change the time to Pacific, and in the process managed to lose the speedometer function. When I finally restored the speed, it was in KMPH instead of MPH. Fortunately I was able to find the original box, with the instructions in it, and able to correct the speed unit and the time. I also changed the calibration, as another reviewer recommended, so it no longer shows speed as 7% higher than actual speed.It would be wonderful if ACECAR put a copy of these instructions on the product page.

Month 1: Reads Zero for first minute, then reads actual speed.Month 2: Reads Zero for first 2 minutes, then reads actual speed.Month 3: Reads Zero for first 5 minutes, then reads actual speed.Month 4: Reads Zero for first 10 minutes, then reads actual speed.Month 5: Reads Zero for first 20 minutes, then reads actual speed.Month 6: Reads Zero for first 30 minutes, then reads actual speed.

I was under the impression that this unit had GPS capabilities and would know the speed limit on the road you were on. It appears that I can only set an alert for one speed at a time. So...I need to look at the speed limit on the sign, pull over and enter it into the unit, then drive until the speed limit changes, repeat?If I am doing this wrong, I would happily change my review, but I cannot seem to get any useful information on it.Can you set it to alert x mph or x% over the speed limit for whatever road you are on?

I tested the first unit with it sitting on my desk, it stopped working after a short time, dead - nothing. I tried several other power cables, no joy.When the second unit arrived, I carefully handled and tested the unit on my desk.I tested my existing Micro USB cables with a phone and a tablet, flexing and moving the cable near the input, there was no connection loss.I used the included USB Micro USB cable as well as mine. with the GPS Speedometer.I quickly saw the loss of power when moving the cable around, not rough, but enough to check for connection.It appears to me, the Micro USB connector in the GPS Speedometer may be a problem.I took a chance and used (removable) hot glue to secure the connector to the unit. The unit worked OK on the desk and then I installed it on my golf cart.It worked fine, no power loss.The compass, the GPS and clock all worked perfect. The speedometer was accurate to within 1 mph from 1 mph up to 25 mph.I can't seem to set the clock to 12 hr format.After some minor issues I'm satisfied.