Transmission

0 miles? Is this a replacement engine/transmission? Lift the front end and firmly set the parking brake. Start the engine and shift to Reverse. Find the shifter mounted on the transmission and make sure it is fully engaged. Do the same for the other drive gears.

If it shifts into gear properly, and the engine just revs when you depress the accelerator pedal, the clutches inside the transmission are slipping. Check the fluid level and condition. If the fluid is brown and/or smells burned, have it changed. If this still doesn't help, pour about half a cup of brake fluid into the transmission dipstick tube. The brake fluid will swell rubber seals and gaskets. This is only a stop gap procedure, but will give an experienced transmission technician a better idea of where the problem lies.