This is part of EPA+DOE's list and this time it is a list of the least fuel efficient cars in ecah class:

[Class Model City/Highway MPG]

Two Seater - Lamborghini Murcielago (manual) 8/13
Minicompact Car - Aston Martin DB9 Coupe, Volante (manual) 10/16
Subcompact Car - Bentley Continental GTC 10/17
Compact Car - Bentley Azure 9/15
Midsize Car - Ferrari 612 Scaglietti (auto) 9/16
Large Car - Bentley Arnage RL 9/15
Small Station Wagon - Audi S4 Avant (manual) 13/20
Midsize Station Wagon - Mercedes-Benz E63 AMG Wagon 12/18
Sport Utility Vehicle* - Mercedes-Benz G55 AMG 11/13
Minivan* - Toyota Sienna 4WD 16/21
Pickup Truck* - Rousch Performance Stage3 F150 11/15
Van (Passenger and Cargo)*
Passenger - Chevrolet G1500/2500 EXPRESS 2WD 12/16
" Chevrolet H1500 EXPRESS AWD "
" GMC G1500/2500 SAVANA 2WD "
" GMC H1500 SAVANA VAN AWD "

Cargo

Chevrolet G15/25 VAN CONV 2WD "
" Chevrolet H1500 VAN CONV AWD "
" GMC G15/25 SAVANA 2WD CONV "
" GMC H1500 SAVANA AWD CONV "