Chart ToolTip using #VALX as Key of a dictionary

[PozzaVecia]

I created a chart showing a data serie including X value year and Y value MarketValue of my cars' collection. Suppose I have a dictionary containing car model and car year. Using the mouse on the chart I need to visualize X and Y value and the name of car model. To show X and Y I use the following code:

chart1.Series["CAR"].ToolTip = "Year: #VALX MarketValue: #VALY"

If I want to show also the model name, any idea?

Dictionary D = new Dictionary();
D.Add(1982,"Cinquecento");
D.Add(2000,"Espace");

chart1.Series["CAR"].ToolTip = "Year: #VALX MarketValue: #VALY Model: "
// here I need to get the model from dictionary associed to the year (#VALX) and add it

Any idea? Thanks for your time