SWR Discrepency Between Meters

[Gerowen]

So I have a Cobra 148 GTL with a 36" Lil' Wil' antenna in my Ford Explorer, and I have a question. It has always had higher SWR than the same setup in my Dodge pickup and the house radio (Both of those are pretty close to a 1.0 all the way from 1 to 40). The whip is seated as far down in the base as it can go.

Using the meter on the radio, I get an SWR reading on channel 1 of a 1.0, and an SWR on channel 40 of about 1.7.


Using an inline meter, a Workman SWR-2T, with a 3 foot jumper coax, I get an SWR reading on channel 1 of 1.0, and a reading on channel 40 of just above a 3. I don't spend a lot of time on higher channels, but it is a tad concerning. Would you trust the Workman meter more or the one in the radio? Could the additional 3 feet of coax from the radio to the meter be causing the increased SWR?

I tried lengthening the antenna just to check by loosening the screw and pulling the whip up about 1/8" at a time and tightening it down, then re-measuring SWR, and as expected, it went even higher as I lengthened the antenna, so I pulled it back down.