Fizzy Fuels can be bought at Fillmore's Organic Fuel Shop. They range from 100 to 200 coins. Each fizzy fuel make your car make a funny noise with an effect. You can hold up to 4 different fizzy fuels at a timer and hold 10 of each. To use a fizzy fuel, press one of the buttons (after purchasing). The buttons are located on your dashboard surrounding your horn button.
Flurp - Your car gives out a burp - 100 coins
Fluuuuuurp - Your car gives out a longer burp then the first one - 100 coins
Gastro Blasto - Your car cleans out those noxious fumes and lets them out VERY LOUDLY - 200 coins
SBD Energy - Your car cleans out those noxious fumes and lets them out very quietly - 200 coins