While this process can be difficult and hard work for real, not digitally is isn't

1. After bringing your image into Photoshop call up the layers palette (F7) and rename the thumbnail titled background by double clicking the word background as shown below.

If your image is in colour, desaturate it by selecting Image/Adjust/Desaturate and then carefully select round the edge of the car using the lasso tool.

Choose Select/inverse and then Edit/cut which will remove the background and leave the car floating on a transparency as we show below.

TIP. Make sure that when cutting out objects that you feather the edge of the selection before carrying out the copy/paste command. This will ensure that when you place the car or the object back into a scene the result looks believable. Without feathering the selection, the result often looks false. The degree of feather depends on the ppi being used and some experimenting may be necessary, but for a 300ppi file try 3 pixels.

Create a new blank layer above your car by clicking the centre icon at the bottom of the layers palette and then fill this layer with a bright bold colour of your choice.

While holding the Alt key move the cursor over the line between the two thumbnails on the layers palette until you see the cursor change to two linked circles and click the left mouse which will wrap the colour over the car taking on it's shape as we show below.

By reducing the Opacity in the layers palette to 70% and selecting soft light from within the layers palette, the car's colour will be changed. You can easily remove any over spill of colour from parts like the windscreen and tyres using a layer mask or just the eraser tool

This is the result you can achieve shown below.

Place the car back onto it's own background or create a new one for effect.

TIP. If you have masked the grille and tyres of the car using a layer mask try changing the colour of the coloured layer or import another image like the examples shown.