Eruptions of the Yellowstone volcanic system have included the two largest volcanic eruptions in North America in the past few million years; the third largest was at Long Valley in California and produced the Bishop ash bed.
On the diesel Passat, the TDI badge stands for Turbocharged Direct Injection, which isn't really all that helpful as the gasoline-powered Passat is also turbocharged and also uses direct injection. Volkswagen attempts to clear this up by calling this Passat the Passat TDI Clean Diesel.
Our verdict on the Audi A4 2.0 TDI Avant. The design of this A4 is tried and tested, and with many improvements having been made to efficiency and running costs. It's a known quantity, but better in ways that can't be doubted.It cruises quietly, boasts economical engines and feels well made.ur verdict on the Audi A4 2.0 TDI Avant. The design of this A4 is tried and tested, and with many improvements having been made to efficiency and running costs. It's a known quantity, but better in ways that can't be doubted.