You can pay tens of thousands of dollars for a flexible-fuel vehicle. Or, you can spend just a few hundred and do it yourself, with the Full Flex Gold.

The conversion kit takes a bunch of cables, connects them to the car’s battery, fuel injectors, and main computer unit. It takes all of 20 minutes.

What happens next is that the Full Flex Gold instructs your car’s main computer to hold the fuel injectors open long enough for ethanol to burn. You can run E85, E100, or plain old petrol without having to flip any switches when you, well, switch.

A Full Flex kit for a 4-cylinder engine will set you back just US$300. The 8-cylinder variety is all of US$510. Somewhere in the middle is the 6-cylinder kit, at US$400.