Interesting and not too bad. I'd watch...
A few suggestions if you're serious about continuing.
One is a camera rig, they can be made and eliminate the movement when carrying the camera while shooting video. Two a boom mic or shotgun mic. Three, lighting... Using a reflector or light to eliminate shadowing during daytime. Last is don't use auto-focus, it's best to zoom in, focus manually, then pull out, everything will stay focused and if you need to zoom in its already set. Takes a little time but those few items will lend a more finished effect to the end product. Also, there's products available today that'll give even more professional finish that are easy to use. Lower thirds (bars with info on bottom of screen) and such to give info that wasn't mentioned while filming, etc., makes up for a lot of ground, as mentioned, spec's on the engine or car, $ into build, etc.
Good work though really!
: )