<p>Although it's a key component of the latest budget proposal from the Senate Republican leader, a $4 billion hike in taxes paid by car owners has been targeted by the GOP for a court challenge, officials said Thursday.</p>
<p>The tripling of the vehicle license fee, which would cost the average car owner about $130 annually, is expected to be triggered in the coming days by Gov. Gray Davis. Along with most Democrats and at least some Republicans, Davis says state law allows him to return the tax to 1998 levels if cash reserves fall to dangerously low levels.</p>