Little Details

I've googled "MPG" + van, "Miles per gallon" + van, and other such combinations, but without luck. Here are my questions:

1) The year is 1975. The characters are in London. One has a van. How many miles per gallon would the average van get? Make is unimportant.

2) What capacity might the tank be (how many gallons--or whatever the British measurement would be)? Again, the make of the van doesn't matter.

3) How much did gas (petrol) cost in 1975 in Britain? Estimations are fine.

Thanks guys--great as usual.

Time/Place: modern day, n/a

Okay, I'm writing a section of a story where an injured person stumbles across a very expired bottle of oxycodone (at least 10 years past expiration date, in a semi-humid environment) and I'm trying to figure out what the side effects might be.

I've googled 'oxycodone, side effects, and expiration' in various combinations, and found tons of information on the standard side effects of the drug, but nothing on what happens when the drug passes it's expiration date. Does it stop working as a pain killer, does it become toxic, does it cause random mutations, or what? Any help is appreciated, thanks.

[Edit: Thanks for all the help guys! I think I'm going to have them fail as a pain-killer, but make her dizzy and nauseated on top of being injured. It'll make the 'stumbling to freedom' bit even more angst-ridden. ;) ]