hi i wanna do a car cake the dimensions are 20 cm length and 8 cm width 

i have a 24cm round cake pan and a rectangular pan with dimensions 27*17cm

which is best to use for the cake 

ps. im gonna be bakin' a chiffon cake

 Seems to me (and with half a lifetime between me and my last science class, I had to do the actual calculations in order to visualize a pan with Metric dimensions) that the "loaf pan" (English dimensions roughly 6.7" x 10.6") would be would almost certainly be the better choice for sculpting a car with minimum waste. Also, your projected finished size of 20 x 8 cm (around 3" x 8" English) seems like it would not produce a whole lot of servings; depending on how high your loaf is when it comes out of the oven, you might want to scale it up to fit the available cake.

Best of luck; I've never attempted to sculpt a cake, myself.

thanks for answering this cake cake is gonna be ffor  me and my husband so i wanna make a small one 

Hi There,

I would use the rectangle tin as awell. Last car cake I made I used a rectangle tin, cut and stacked the cakes, then carved it down to shape. Most cars are really rectangles that have smooth edges, if that makes sense? Have fun with it. Love doing car cakes!