668
‘‘(1) the sum of the regular tax liability (as de-
fined in section 26(b)) plus the tax imposed by sec-
tion 55, over
‘‘(2) the sum of the credits allowable under sub-
part A and sections 27 and 30A for the taxable
year.
‘‘(d) DEFINITIONS.—For purposes of this section—
‘‘(1) QUALIFIED ADVANCED LEAN BURN TECH-
NOLOGY MOTOR VEHICLE.—The term ‘qualified ad-
vanced lean burn technology motor vehicle’ means a
motor vehicle—
‘‘(A) the original use of which commences
with the taxpayer,
‘‘(B) powered by an internal combustion
engine that—
‘‘(i) is designed to operate primarily
using more air than is necessary for com-
plete combustion of the fuel, and
‘‘(ii) incorporates direct injection,
‘‘(C) that only uses diesel fuel (as defined
in section 4083(a)(3)),
‘‘(D) the city fuel economy of which is at
least 125 percent of the 2000 model year city
fuel economy for a vehicle in the same inertia
weight class, and
669
‘‘(E) that has received a certificate that
such vehicle meets or exceeds the Bin 8 Tier II
emission level established in regulations pre-
scribed by the Administrator of the Environ-
mental Protection Agency under section 202(i)
of the Clean Air Act.
‘‘(2) LIFETIME FUEL SAVINGS.—The term ‘life-
time fuel savings’ means, with respect to a qualified
advanced lean burn technology motor vehicle, an
amount equal to the excess (if any) of—
‘‘(A) 120,000 divided by the 2000 model
year city fuel economy for the vehicle inertia
weight class, over
‘‘(B) 120,000 divided by the city fuel econ-
omy for such vehicle.
‘‘(3) 2000 MODEL
YEAR
CITY
FUEL
ECON-
OMY.—The 2000 model year city fuel economy with
respect to a vehicle shall be determined in accord-
ance with the following tables:
‘‘(A) In the case of a passenger auto-
mobile:
‘‘If 
vehicle 
inertia 
weight
class is:
The 2000 model year city fuel
economy is:
1,500 or 1,750 lbs ....................................................................
43.7 mpg
2,000 lbs ..................................................................................
38.3 mpg
2,250 lbs ..................................................................................
34.1 mpg
2,500 lbs ..................................................................................
30.7 mpg
2,750 lbs ..................................................................................
27.9 mpg
3,000 lbs ..................................................................................
25.6 mpg
3,500 lbs ..................................................................................
22.0 mpg
670
‘‘If 
vehicle 
inertia 
weight
class is:
The 2000 model year city fuel
economy is:
4,000 lbs ..................................................................................
19.3 mpg
4,500 lbs ..................................................................................
17.2 mpg
5,000 lbs ..................................................................................
15.5 mpg
5,500 lbs ..................................................................................
14.1 mpg
6,000 lbs ..................................................................................
12.9 mpg
6,500 lbs ..................................................................................
11.9 mpg
7,000 or 8,500 lbs ....................................................................
11.1 mpg.
‘‘(B) In the case of a light truck:
‘‘If 
vehicle 
inertia 
weight
class is:
The 2000 model year city fuel
economy is:
1,500 or 1,750 lbs ....................................................................
37.6 mpg
2,000 lbs ..................................................................................
33.7 mpg
2,250 lbs ..................................................................................
30.6 mpg
2,500 lbs ..................................................................................
28.0 mpg
2,750 lbs ..................................................................................
25.9 mpg
3,000 lbs ..................................................................................
24.1 mpg
3,500 lbs ..................................................................................
21.3 mpg
4,000 lbs ..................................................................................
19.0 mpg
4,500 lbs ..................................................................................
17.3 mpg
5,000 lbs ..................................................................................
15.8 mpg
5,500 lbs ..................................................................................
14.6 mpg
6,000 lbs ..................................................................................
13.6 mpg
6,500 lbs ..................................................................................
12.8 mpg
7,000 or 8,500 lbs ....................................................................
12.0 mpg.
‘‘(4) MOTOR VEHICLE.—The term ‘motor vehi-
cle’ has the meaning given such term by section
30(c)(2).
‘‘(5) CITY FUEL ECONOMY.—City fuel economy
with respect to any vehicle shall be measured in ac-
cordance with testing and calculation procedures es-
tablished by the Administrator of the Environmental
Protection Agency by regulations in effect on April
11, 2005.
‘‘(6) OTHER
TERMS.—The terms ‘passenger
automobile’, ‘light truck’, and ‘manufacturer’ shall
have the meanings given such terms in regulations
prescribed by the Administrator of the Environ-
671
mental Protection Agency for purposes of the admin-
istration of title II of the Clean Air Act (42 U.S.C.
7521 et seq.).
‘‘(e) CARRYFORWARD ALLOWED.—
‘‘(1) IN GENERAL.—If the credit amount allow-
able under subsection (a) for a taxable year exceeds
the amount of the limitation under subsection (c) for
such taxable year (referred to as the ‘unused credit
year’ in this paragraph), such excess shall be allowed
as a credit carryforward for each of the 20 taxable
years following the unused credit year.
‘‘(2) RULES.—Rules similar to the rules of sec-
tion 39 shall apply with respect to the credit
carryforward under paragraph (1).
‘‘(f) 
SPECIAL
RULES.—For 
purposes 
of 
this
section—
‘‘(1) REDUCTION IN BASIS.—The basis of any
property for which a credit is allowable under sub-
section (a) shall be reduced by the amount of such
credit (determined without regard to subsection (c)).
‘‘(2) NO
DOUBLE
BENEFIT.—The amount of
any deduction or credit allowable under this chapter
(other than the credit allowable under subsection
(a)), with respect to any vehicle shall be reduced by
the amount of credit allowed under subsection (a)
672
(determined without regard to subsection (c)) for
such vehicle for the taxable year.
‘‘(3) PROPERTY USED BY TAX-EXEMPT ENTI-
TY.—In the case of a vehicle whose use is described
in paragraph (3) or (4) of section 50(b) and which
is not subject to a lease, the person who sold such
vehicle to the person or entity using such vehicle
shall be treated as the taxpayer that placed such ve-
hicle in service, but only if such person clearly dis-
closes to such person or entity in a document the
amount of any credit allowable under subsection (a)
with respect to such vehicle (determined without re-
gard to subsection (c)).
‘‘(4) 
PROPERTY
USED
OUTSIDE
UNITED
STATES, ETC., NOT QUALIFIED.—No credit shall be
allowable under subsection (a) with respect to any
property referred to in section 50(b)(1) or with re-
spect to the portion of the cost of any property
taken into account under section 179.
‘‘(5) ELECTION
NOT
TO
TAKE
CREDIT.—No
credit shall be allowed under subsection (a) for any
vehicle if the taxpayer elects not to have this section
apply to such vehicle.
‘‘(6) INTERACTION
WITH
AIR
QUALITY
AND
MOTOR VEHICLE SAFETY STANDARDS.—Unless oth-