Are you acknowledging that each car has its own velocity and that each car's velocity changes as it accelerates?
Each car has a velocity. Each car experiences acceleration, which changes its velocity.
Sounds to me like what you are describing is an absolute motion of the car in space, with its own velocity, independent of other objects.
No, I'm describing a change in velocity. There is an inertial frame associated to the cars at the start, namely the one associated to their rest frame. No need for an absolute frame. The cars accelerate and then stop accelerating, putting them in a different rest frame. Two frames, moving relative to one another, no requirement for an absolute reference frame.
Reference frames are like coordinate systems. In the first inertial frame the cars at at rest initially and at some speed v at the end. If we worked in the end reference frame then the cars start at speed -v and end at speed 0. If I worked in some other reference frame then they start at speed V and end at speed V+v. Where they at any moment in time requires careful calculation using Lorentz transforms and worldlines but they don't require the use of an absolute reference frame.
This is precisely the point I have made several times to you. You don't know what SR says, you don't know how references work within it, you don't understand
any of it and thus you just jump to utterly unsupported conclusions based on your ignorance. You obviously don't have the intellectual honesty (and I doubt you have the intellectual capacity even if you were intellectually honest) to find out what SR actually says or to stop jumping to utterly unsupported conclusions. As such you're not worth spending significant time on. Fortunately your laughable attempts at 'disproving' relativity are so terrible, thanks to your shortcomings as a physicist, little effort is usually required to blow them out of the water.
As origin says, did you even think about what I said or did you just try to find a sentence which you think you can twist into something for your own gain? If you know you're doing it then you should realise how obvious that behaviour is. If you don't realise you're doing it then I'll tell you now, it is obviously a dishonest action on your part.
I'm just trying to figure out what you mean by wasting time. How do you waste time? Doesn't time always elapse in full? Isn't it impossible to waste time?
I really hope you're attempting to be humorous or you're not a native English speaker. The alternative is that you're even more dense than I thought (and that's pretty bad already).