The already athletic Audi TT gets even leaner for their latest concept, the TT Ultra Quattro. Weighing in at 2,449 lbs, the car packs a 310 hp 2.0 TFSI engine which gets the TT from 0-62 in 4.2 seconds. A comprehensive recipe of aluminum, fiberglass, titanium, and various other tweaks helped Audi create a car that's 661 lbs lighter than the production model, a lean figure that helps the TT Ultra Quattro reach a top speed of 174 mph.

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