Some years back I used to verify the VIN numbers for an insurance company, some are very difficult to see even in good light, one method that I found was to use a small flash light and place it horizontal to the numbers, with a cardboard shielding the sun.
Or read them at night with the flash light, I photograph my passport next to the VIN on the dashboard, having this allows me to enlarge the photo so that the numbers are more legible, sometimes you need to turn the flash off or turn it on depending on the angle of the windshield or shine the light on the tab with the numbers.
navegator