as most are aware regular gas prices are plunging which is putting the pinch on oil exporters and handing a $75 billion tax cut to the U.S. but as a long-time TDI driver i watch the diesel price which is spiking. currently, in wisconsin, there’s a $1.20 per gallon difference between regular and diesel – hence “Black-Market Diesel: Thieves Sell Fuel By The Truckload”. pop quiz, when was the last time diesel was cheaper than regular gas? 2002 which was the first year we bought a diesel.