I own a 2002 Prius with DRL's and do not regret the purchase of the option. However, there are times when you don't want any lights on. I have installed a DRL override circuit on my Prius last weekend and it works great. The circuit consists of the addition of a 1000uf 25V capacitor, a small rectifier diode, a pushbutton switch, and a DPDT relay from Radio Shack. All the parts cost about $10.
Installation involves unbolting the passenger side underhood fuse block and turning it upside down. A wire (the one from the DRL relay to the ground side of the headlamps) must be cut. The relay contacts are placed in series with the cut lead. A pushbutton switch mounted at the base of the dash requires a small lead to be routed to it from the circuit (capacitor, diode, and relay) mounted under the hood.
Once the Prius is started, and the parking brake released, the DRL's come on as always. When the pushbutton switch is depressed the DRL's are shut off. If you turn on the headlights, the circuit is reset and when the headlights are shut off the DRLs come back on. Using the headlight switch for "flash to pass" does not reset the circuit to turn off the DRL's unless you hold the headlight stalk on for about two seconds. The nice thing about the mech is that it always reverts back to DRLs each time you start the vehicle--so you don't forget. The mod results in no current drain on the vehicle 12 volt battery when the Prius is "off".
Installation took me a good 3 hours (obviously it was the 1st time--but I am an electrical engineer) and it is not for those who are not comfortable in wiring simple electrical components, splicing and routing wires.
If there is interest I can post the circuit and some pics on the installation. This is the way that DRL's should have been wired in the first place.
