In other respects, the 2005 scenario projections are relatively mundane. In 2005, the 3.0L V-6
engine is expected to be replaced by a 2.3L, four-valve four-cylinder engine with variable valve
timing,l2 and the four-speed automatic transmission will be replaced with a five-speed automatic.
There are no differences in the assumptions on the types of drivetrain technologies for 2005
between the mean and optimistic scenarios, but the benefit for each technology is different,
leading to different fuel economy estimates. In many respects, the 2005 hypothetical vehicle is not
technologically very different from the baseline 2015 vehicle. The 2015 baseline vehicle, however,
is expected to use a 2.5L V-6 and offer better performance and comfort than the 2005
hypothetical vehicle, which explains the difference in fuel economy.
For 2015, the mean scenario includes the weight projections discussed above, and includes the
use of a direct injection stratified charge (DISC) engine with variable valve timing. This assumes
of course, that lean nitrogen oxide (NOx) catalyst technology is perfected to meet a NOX standard
of 0.2 g/mile. The reduced weight results in a small displacement engine, and the resultant fuel
economy estimate is 53.2 mpg. It is also possible that the direct injection diesel can meet this
stringent emission standard by 2015, and OTA has estimated its fuel economy at 59.0 mpg on
diesel fuel The high efficiency of the DISC engine essentially narrows the difference between
gasoline and diesel versions to almost identical levels on an energy content basis as diesel has
about 12 percent more energy per gallon than gasoline. The optimistic 2015 scenario forecasts
a hypothetical vehicle with a carbon fiber body and a small displacement DISC engine, and
is estimated to attain 63.5 mpg.
Price differentials (over prices of the 1995 Taurus) of the vehicles are calculated using the
methodologies described in appendix B, and are mid-range estimates. Uncertainties in incremental
price are about ±10 percent for 2005 estimates and ±20 percent for the 2015 (m) estimates. The
2015(0) price estimates are extremely uncertain owing to the wide variations in potential future
price estimates for carbon fiber based body construction. These estimates do not include the cost
of emission control and safety related equipment (which do not vary across scenarios), with one
exception. For the 2015 cases, the incremental cost of the lean-NOX catalyst for the DISC and
diesel is included, because the conventional engines in the baseline will not require such a catalyst.Improvements to other market classes (subcompact, van, pickup) are quite similar to those for
the hypothetical Taurus, allowing for some variation in baseline technology. For example, the
absolute drag coefficients for the compact van and pickup truck are different from those for cars,
but the percentage reductions relative to the base are quite similar. The only major exception to
this similarity in technology improvements is for the pickup truck; owing to its greater weight,
meeting a 0.2 g/mi NOX standard is considered very difficult and, hence, the DISC is adopted only
in the “optimistic” scenario for 2015.While estimates of intermediate car fuel economy of 53 to 65.5 mpg in 2015 may seem
remarkably high, there currently are some highly fiel-efficient cars that rival this type of
performance. For example, VW produces a 1.9L turbocharged direct injection (DI) diesel car(^12) Low speed performance is kept constant by controlling the variable: Torque x Axle Ratio / Weight to the baseline level, based on Torque at
2000 RPM, an engine speed typical of 30 mph in second gear or 45 mph in third gear. This leads to an axle ratio of 3.18, which would normally be
very low for a 4-valve engine. However, in this ease. the VVT is optimized for low speed torque making the low axle ratio possible.