The figures are from the Directgov web site.
From April 2010, already registered higher emitting cars will be charged up to £30 more and lower emitting cars will be charged up to £30 less.
Band       CO2 (g/km)       2010-11 standard rate 
A       Up to 100             £0 
B       101-110             £20 
C       111-120             £30 
D       121-130             £90 
E       131-140             £110 
F       141-150             £125 
G       151-165             £155       
H       166-175             £180 
I       176-185             £200 
J       186-200             £235 
K*       201-225             £245 
L       226-255             £425 
M       Over 255             £435
*Band K includes cars that have a CO2 figure over 225g/km but were registered before 23 March 2006.
What you will pay if your car uses alternative fuel such as electricity or gas
Alternative fuel cars include gas-propelled vehicles, and those capable of being propelled by petrol and gas or electricity and petrol/diesel.
Band       CO2 (g/km)       2010-11 alternative fuel rate 
A       Up to 100             £0 
B       101-110             £10 
C       111-120             £20 
D       121-130             £80 
E       131-140             £100 
F       141-150             £115 
G       151-165             £145       
H       166-175             £170 
I       176-185             £190 
J       186-200             £225 
K*       201-225             £235 
L       226-255             £415 
M       Over 255             £425
 
How to find out what your car’s CO2 emissions are
To find out the CO2 emissions of your car, you can either:
check your registration certificate (V5C) 
enter the make and registration mark of your car into the online ‘vehicle enquiry’ section on DVLA’s Electronic Vehicle Licensing website