v1 works great in one car and shows a laser alert in my other car Please help???

[j315]

my v1 works great in my 2003 passat with a fuse box hard wire,concealed display and remote mute button. but when i use it in my 1972 mgb with the cigarette lighter it reads a false laser about 70% of the time. i have also used my friends v1 in to test it and it did the same thing. any help would be greatly appreciated.

[NormSky]

When V1 with laser was first introduced power fluctuations would false laser. How many volts at the cigg?

[category4]

Weren't some of the British cars from that era + ground?