xy charts??

I can visualize a simple surface (= 2 dimensional?) chart with independent variables on the x and y axes respectively and the dependent values graphed against each. As I said I've a feeling that x y charts do this, with or without dual axes, but I can't quite figure out how to do it. Trial and error?

I have a feeling that no x-y charts do this. You need need three independent axes.

If you wanted to chart (for example) the second hand values of a model of a car against the age and the mileage as displayed in various used car adverts, I can't see why Excel cannot do this (without resorting to 3 axes - I can't think in 3 dimensions!). There are only two independent variables to go on 2 independent axes. I thought this was what x y charts were designed to do.

Maybe. Draw one by hand, scan it and post it.

for xyz points you can try this
http://www.andypope.info/charts/3drotate.htm

Tks - the contents look really interesting even if I don't believe that for my simple purposes it's necessary to go to 3 dimensions let alone rotate them! I just need to get the hang of using standard xy charts properly and I suspect that somewhere within what you've sent will be the answer. Weekend's work ahead ..

Probably for you example of the car you need

X axis milage
Y axis age
Data label text is the car and cost

Use this free addin to link data labels to cells.
http://www.appspro.com/Utilities/ChartLabeler.htm