Driving lights, by definition, come on with your high beams; they mount above the bumper and are narrowly focused, straight-ahead lights. You'd probably be better off by switching to e-code lenses and upgrading your lamps, first.

E-codes are the European lenses which put a lot more light on the pavement - and the high beams are like the landing lights on a 747. Should cost about $250 for the pair and they take about 1/2 hour to install.

You can upgrade the low beam halogens to Philips VisionPlus (Euro lamps designed for ecodes, available at http://www.autolamps-online.com). They're $40/pair and increase light output by 50% over stock halogen. Not needed for the high beams.

If you're willing to commit more money to the lighting project, you can upgrade from halogen to HID for about $400, also at the autolamps-online site.

You can add around-the-corner lighting with a good set of foglights. The Volvo OEM are excellent, made by Hella and variants are found on both MB and BMW. If you're clever and mechanically inclined, Hella MicroDE foglights are even better....but you'll be making a custom installation. You can patch them into the OEM foglight wiring which is already in your car.
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David (98 S70 T5SE Black, misc mods (mostly lighting), red calipers) (92 940GLE)