There is pro software like Protools, Wavelab, Adobe Soundbooth, etc, but they are pretty pricey. There is free software called Audacity.
Sourcing the sound is touchy, youtube is not very good quality, even with a HD mp4 the sound is compressed, much like a jpg is compressed. The final sound is wav which is uncompressed so if you source the sound from youtube you will not end up with the correct end product.
The right way to source the sound is take a decent fullrange microphone and record the car twice, once inside and once outside, revving from idle to redline then back to idle. Then you take that sound file and break it up, say it redlines at 6000, you cut it at 2000 and 4000, so you have 3 parts, idle to 2000, 2000 to 4000, 4000 to 6000. *(that value is not concrete, it depends on a few different factors, ie, there is a powerband where the pitch will change faster, so you want to cut it at the point it changes)*. Then you take a pitch shifter and from the middle point bend the sound up from the low end and down from the high end so you end up with a flat pitch in the middle.
Then you need to set up the sfx file, but I have nfi how that works, I'll let someone else explain that bit
