If your vehicle is showing rpms go up but car doesn't accelerate, here are the most likely causes and the parts you'll need to fix each one.
On manual transmission vehicles, the clutch friction material wears down over time. When it gets too thin, it slips against the flywheel instead of transferring engine power to the wheels.
Automatic transmissions require precise fluid pressure to engage internal gears. Low fluid levels due to a leak or improper filling will cause the internal clutches to slip.
If the clutch master or slave cylinder is failing, or if air was left in the lines after a recent installation, the clutch may not fully engage, causing it to slip under load.
Over time, the internal clutch packs, bands, or the torque converter inside an automatic transmission can burn up or wear out, resulting in a loss of power transfer.
If a CV axle snaps, the transmission will spin the broken axle freely instead of moving the car. The engine will rev, but the vehicle will barely move or not move at all.