Dive-away should be smooth, with no lurching, sputtering or odd noises. The car should accelerate smoothly and maintain power when climbing hills. After the engine warms, accelerate to about 45 mph, Take your foot off the accelerator for a few seconds, and then accelerate. Your helper should be with you inside the car, watching through the rear window for exhaust smoke. Black smoke may mean only that the fuel system needs adjusting.
Blue smoke means that the car burns oil.
Persistent, billowy white smoke could indicate that coolant is entering the engine's combustion chambers through a blown head gasket or crack in the cylinder head or engine block. Smooth shifting is the key here. A manual clutch should engage smoothly, without bucking. The fluid should be reddish, with a faint odor of chestnuts. A dark-brown color, a rancid smell or metal particles on the dipstick indicate trouble.