The new window sticker says the B6 gets 21 / 30 mpg.
I think USP reduces the drag coefficient by a little, making it get slightly worse MPG.
I'm only going by the cluster reading. I haven't tried any other ways such as hand calculations or apps such as Fuelly, to try checking the accuracy of it.
Lately, mine as dropped to about 23 combined, due to the bellypan being off.
I think that at speed, the bellypan might help airflow with the ducts underneath, to create a vacuum to suck out air and cool the engine.
Assuming the front cooling units (radiator and A/C condenser) aren't too covered in dust, that vacuum should also help pull air in through them.
My side grill is also pass-through instead of solid with a block-off plate behind it. Maybe one of those would help.
Maybe it depends on how the car is driven, and if it cruises for a long time around 65mph or not.
Because at that speed, there's not too much air resistance, and the car has already built up momentum.
There's probably less gear resistance from the transmission in a higher gear, and all the spinny parts have spun up to speed (wheels, brakes, etc.)
As for other things, I think somebody said renewing their PCV hose system helped get some more MPG.
My car is basically stock at 160k miles, so all of that stuff is still old, crusty-looking, and original.
Also, I don't have the additional transmission bellypan, or anything for the back of the car. Which I think might have to be custom, since there might be no stock parts.
Whereas certain other cars I've seen, they have plastic smooth aerodynamic covers that mount to the lower rear suspension.
IDK if direct injection fueling in newer cars helps them get more MPG.
Not sure if clutch choice makes a difference.
There's also diesel vs. gas engine, but a swap would probably be difficult and costly.
Maybe automatic cars are better for the city?
IDK if mods help, such as exhaust parts, tune, etc.
Would a wheel bearing refresh help, good tire pressure, maybe lighter wheels such as BBS RK's, and making sure the suspension parts (bushings) are good, straight, and dialed in?
Also, IDK if seats make a difference. Such as heavy power Recaros, versus lighter manual-adjustment seats.
I wonder what B7 2.0T's get.
I mean, there's still whole other cars, like certain Volkswagen TDI's and Mercedes CDI diesels, which may cost a bit more but get more MPG.
Someone told me that due to higher compression (but still iron block), diesels can tend to leak from places more.
Certain years though. Like if it's a MK4 Jetta, it'd be '99.5-'03 or '04, for the ALH-code. And certain earlier CDI's, before stuff got strangled with more emissions equipment, making them rarer, more sought-after, and thus a higher price.
Would it help to do a refresh service on the fuel injectors? What about cleaning the combustion chamber? Hopefully the piston rings aren't carbonized.
Aren't there various treatment products for that?
Fuel filter? What shape is the fuel system in, such as all the pump parts under the seat?
Honestly IDK, because at the same time, it's still kind of a Volkswagen engine (MK4 GTI, Jetta, etc.) put into a big heavy AWD Audi, instead of Fronttrak FWD, especially a working CVT for optimal gear ratio.
And you mention city-driving, so maybe a different 6th gear wouldn't help. But the regular 6th gear may already be fine.
I think someone recently mentioned the idea of getting more MPG by using thinner gear oils.
I wonder if engine oil choice and potentially using an additive could make a difference.
But still. City.
Maybe for citys, people choose different vehicles?
Chevy Volt, Prius, Honda Fit, etc - anything really...
There's also wheel aerodynamics, but all of these little things may only be small differences.
I hear the Audi uses an N80 valve to burn tank vapor on deceleration/stopping in gear but off the gas pedal.
But what about other cars, such as a hybrid or electric car, that can use the electric motor to slow it down in your "50 city stops" rather than eating through brakes and using clutch?
Isn't this why people get rid of such cars in city areas like San Francisco, or rich people keep them garaged for only occasional use?
And what if a manual incentivizes you to get into trouble doing a "rolling california stop" to avoid clutching out into neutral to get back into 1st, doing the whole foot dance while a lazy automatic car behind you wonders whats going on.
On a cold night with little traffic, maybe manual seems nice. It's breathing fresh dense air and nobody is in the way. But IDK about traffic...
What do delivery drivers use? I'm not sure about pizza places.
But car parts delivery services seem to use small economy cars and pickup trucks.
There's also AT&T, with those small van things.
quattro was also based on a Volkswagen Iltis unstoppable military truck,
so basically you're daily-driving a secret Humvee in traffic and people have no idea.
Also road quality. Some areas of the country seem to have smooth roads that get more MPG,
but other areas chew through tires fast and drop the MPG because it's like sandpaper.
It's been a while since I fell running or on a bike, scooter, etc. as a kid to scrape my knee and get a scab, so I totally forgot,
but after a long drive that transitioned between both surfaces, there seemed to be a noticeable drop in both MPG and the feel of the car. There seemed to be more drag that would slow it down, which I doubt comes from the air.
These are all just ideas/speculation though.
Saw a MKVII Jetta advertised at Costco; the MPG seemed not much greater, but IDK about the sticker claim versus what it actually gets in the real world.
I think my old 2.0L 8V Jetta got similar MPG's, but may have had less power. Different gearing, lighter weight, and FWD though.
Hyundai Accent, 28 / 38-45 MPG
- ~$14k
- small
- interior falls apart
- primitive suspension design
- maybe not as safe
- can be automatic
I dunno, what else...
- fuel quality, station choice, and octane rating?
- oh yeah, B6 panels are probably steel, whereas B7 RS4 might have aluminum hood. Not sure about fenders. Carbon fiber aftermarket products exist but they're costly
- sunroof option adds cost from new, and weight (~30lbs?) - on the plus side, that might make it safer, being the only car to beat Volvo at the time, which is a brand known for safety and called Swedish bricks. Not sure if that was due to their former shape, weight (were they heavy?) or both.
- trunk cargo cover in avants, heavy battery, and full size spare might add weight
- quattro AWD gearbox adds weight, at least the big 6spd 02X, because it houses a Torsen center diff. Whereas a RWD gearbox is probably smaller and lighter, to just send power rearward (BMW). Also maybe the 1.8T engine block is cast iron or something. (heavy)
- isn't this why Europeans (higher fuel cost over there) convert their car fueling to CNG, petroleum, etc.?
- old O2 sensors, carbonized exhaust valves?
Even non-USP, it still may not be the best drag coefficient car.
I'm not expecting there to be a lot of room for improvement.
Like when people start commuting far in trucks and notice how fuel-thirsty they are, so they just end up selling them for something else like a Japanese regular car.
IDK enough about cars to tell you if other things make a difference, such as compression, stroke, etc.
Also, the car has a turbo that's always spun by the exhaust gas. Does that worsen MPG when the turbo isn't used to add power efficiently (smaller engine size), because the engine exhaust gas has to spin it? Would it cause resistance when not in boost, making it so that the exhaust can't suck intake air in?
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Originally Posted by dozer103
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