I have something equivalent to this patched into the internal and external speaker arrays (separate amps). There is a switch in the drivers footwell that enables or disables the sound.
To be honest, I seem to remember this kinda stuff being too Las Vegas and 'not screen accurate'? Bit confused..
The other sound effect I've been meaning to do, but haven't wired up yet is the spool up / high-voltage charging sound when the time machine's engine first starts (when in Doc Brown's truck).
Can any one point me in the right direction to get a decent door opening sound from the internet. The ones I come across seem to be poor recordings. Any site recommendation?