which kind of stablizer should i go for a Stable shots for Vehicle

[Shannon Hong]

have a project that needs a clean stable shots for a running vehicle , have tried to attach the camera on the back window of my car using giant sucking discs with tripod head,
and the footage came out ok with slightly shaking btw the gaps .
thinking of get a Gyro stablizer or a wearing steady vest to get a better shots , and which one should i get for this kind of shooting ? any advise will be so much appreciate !!