Confused by car tax brackets

Scotty1.7

I currently run a nice little coupe that all though I love it to bits, is just no longer meetings my needs, with a view to size and space

So I've started to just look at what is around

Decided I'd like a TDi and it to be up to tax bracket 'F' (£135 a year)

Found a nice Golf GT TDi 130 3dr that fits the bill and is in my meagre budget (2k not loaned just saved up other time) which I missed, but gives me hope I'll find one eventually

I've then looked at over VAG cars with this engine and come across something weird that I don't under stand

3 Cars - All Audi's, all 1.9 PD TDi 130 lumps, all SE spec's

A3 147 grams of CO2 - Tax is £135 a year
A4 153 grams of CO2/A6 157 grams of CO2 - Tax is £170 a year

Same engine in all of these cars

Same spec pretty much for all cars

OK there is a size / slight weight difference, but surely this can't have any input to the CO2 the engine outputs?

None of them are Quattros as well, purely FWD

Anyone got any ideas?

TadleyBaggie

The heavier the car the more fuel will be needed to accelerate the car to a given speed. More fuel equals higher CO2 so the figures make perfect sense to me.

flutterbyuk25

This shows the different tax bands. As you can see 150g/km is the cut off for the £135 rate, then it jumps to £170.

daveyjp

It s all about weight. If you look long enough you may find an A3 in the higher tax bracket due to fitted factory options which increase the weight.

Scotty1.7

I've looked on parkers, and the DVLA site, neither of which show them to be in any other bracket on the A3- irrespective of weight, not the be all and end all but its the best I have to look at currently?

It surely can't be based on weight, the engine still out puts the same power and torque, heck they even have the same engine codes?!?!?!

In my eyes, shouldn't that mean the same road tax?

forgotmyname

A heavier car uses more fuel to accelerate.

Otherwise we would all have 3 ton Range Rovers and smile at the pumps
knowing it does 60mpg.

But it doesnt because its heavy.

I think it was the car show 5th gear they got an Astra and timed it up the drag strip. Took out all the interior and anything not needed and it took over a second off the time.
If they did laps it will also have used less fuel.

Remember the Audi adverts for spray style washer jets, They use less water so can use smaller bottles and reduce the weight of the car.