Thanks for your comments/suggestions. On your recropped photo I kept the cones in the picture since they tell part of the story. RallyCross in the US is very different than in Europe. Events are run in a large field with plyons used to define the course. During the day the course often undergoes significant change as cones are moved to redine it. It is very common to create a completely different course for the afternoon by rearranging the cones. Drivers that follow the path worn in the grass in the morning instead of looking for the cones are soon lost.
I have to agree about "washed out." Looking back at them now I'm surprised I didn't realize that. On the Sony laptop I use for editing I have to confess your examples are very dark. This may well say more about the Sony's screen than anything else.
I also have to agree with you about the shutter speeds. As I've gotten older (68) my ability to shoot at the longer times has deteriorated. Even at 1/125 my percentage of keepers drops significantly. Ah for the days when I regularly shot at 1/60! Despite the excuses I need to spend some more time practicing to see if I can't regain some of that ability. I agree that it would definitely improve my photos.
Actually, I used to use the Nikon 70-200 F2.8 and often with the 1.4x teleconverter as you suggest. These were done with the 70-300 F4.5-5.6. It is nowhere near as good a lens but... I rarely make prints anymore and when I do they are usually 4 x 6. Most of my work ends up on the internet or in SCCA newsletters. For these purposes the much lighter weight has made the 70-300 my usual lens for these events. Probably something about being an old fart again.
Thank you again for taking the time to provide me with some valuable insights.