Wiring harness

Just curious is there a harness adaptor for a vectra B which will let me change my stereo but keep all my mpg and other stuff?

yes but not cheap.
best going into your local car audio shop and sitting down when it comes to price!

Lol what do you ask for I'm used to just going Halfords and getting an adaptor

miss halfords.
ask for what you put at the top ^^

Cheers dude