ABG posted an article with an interesting list of mods that new car makers are looking at to improve efficiency.
The interesting bit is they're ranked by cost and effectiveness.
The figures were compiled by the U.S. NRC (national research council):
Code:
SI Techs ...................... AVG Incremental Cost ... Avg Cost for
1% Improvement in
Fuel Consumption
Low Viscosity Lubricants ...................... $6 .......... $12.00
VVT-Coupled Cam Phasing (CCP), OHV ............ $53 ......... $21.00
Variable Stroke HVAC .......................... $80 ......... $22.86
Turbocharging and Downsizing .................. $129 ........ $25.80
Low Rolling Resistance Tires .................. $40 ......... $26.67
Aerodynamics 5%-10% ........................... $45 ......... $30.00
Electric/Hydraulic Power Steering ............. $95 ......... $31.67
Valve Event Manipulation ...................... $52 ......... $34.67
7 Speed Transmission .......................... $235 ........ $39.17
VVT-Coupled Cam Phasing (CCP), SOHC ........... $105 ........ $42.00
VVT-Dual Cam Phasing (DCP) .................... $105 ........ $46.67
Dual Clutch Transmission ...................... $350 ........ $46.67
Continuous Variable Transmission .............. $207 ........ $51.63
8 Speed Transmission .......................... $425 ........ $60.71
Valve Event Manipulation (Variable Value Lift) . $760 ........ $69.09
VVT-Intake Cam Phasing (ICP) .................. $105 ........ $70.00
Cylinder Deactivation, OHV .................... $353 ........ $70.50
Engine Friction Reduction ..................... $95 ......... $75.60
Continuously Variable Valve Lift (CVVL) ....... $450 ........ $90.00
Mass Reduction 5% ............................. $297 ........ $91.38
Mass Reduction 10% ............................ $713 ........ $109.69
Cylinder Deactivation, SOHC ................... $555 ........ $111.00
Full Hybrid ................................... $6,000 ...... $127.66
Discrete Variable Valve Lift (DVVL), SOHC/DOHC . $293 ........ $130.00
Mass Reduction 20% ............................ $1,600 ...... $133.33
Stoichiometric Gasoline Direct Injection (GDI) . $319 ........ $141.78
Conversion from SI to CI ...................... $5,900 ...... $159.46
Stop/Start Hybrid ............................. $885 ........ $221.25
Full article:
At Witz' End - Comparing costs and benefits of fuel-saving technologies — Autoblog Green