You can keep direct injection. I know Toyota has solved the carbon buildup problem with direct injection by having a dual mode system of direct injection and FI. When cruising on highway it switches over to FI. Some manufacturers have not solved the carbon buildup issue yet.
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Iām not at all concerned about carbon build up in Mazda SkyActive-G: it is modest and relatively inexpensive to deal with (here comes a big stone thrown to German brands).
My wifeās car has 83K miles on it now, we performed valves cleanup at 75K miles and it made a small improvements, but it was barely noticeable.
Dealer wanted something like $150 to do this service, they do it routinely and recommend every 50K miles or so.
The original poster wanted more power, here it goes: he can get 2.5 liter engine, which will be āold styleā (non-DI) in used cars and Direct Injected 2.5liters in new 2018 model.
$21K apparently buys a new Touring style Mazda3 with 2.5 liter engine, must be very Zoomy to drive 
Understood. I just prefer more power than needed, rather than āadequateā power. If I was new car shopping, Iād want the higher powered rig, all else being equal. I prefer to not have to downshift as often, and I prefer to move with less throttle input. Not that Iām a boy racer or drive 100 mph. I just like the power. A few (15) peak hp doesnāt translate to a huge difference day to day. But people put cold air intakes on their engines for less gain every day.
I completely understand, my next car will be an E46 330CI with a Quaiff LSD, high flow supersprint exhaust and a full remap because I just want that POWERRR 
I like the Mazda 3. Other cars in this class would be the VW golf GTI, Ford focus ST, and the Kia Forte.
All of which are going to be fun to drive and fairly economical.
Raw horsepower numbers are useless. Knowing horsepower without knowing other factors is like knowing how much someone weighs without knowing anything else about him. OK, John weighs 150 pounds. Does that make him a skinny 30 year old or a morbidly obese 8 year old?
This:
has a lot more horsepower than this:
but I know which one I want to take to the trackā¦
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Itās not trivial at all.
https://us.autologic.com/news/cleaning-carbon-build-up-from-direct-injection-engines
looks like I was not at all out of the blue throwing a stone toward VM/Audi
the second line (Hyundai) is not that bad actually, it had a long way to go before it makes for a noticeable problem
youtube is full of videos showing how to do that on Mazda, their front intake manifold is quite easy to remove to get to the valve ports and eventually clean it, so I can totally see why dealer is charging a reasonable under $200 to do it
Which one are you hauling rock with?
Same type vehicle vs same type vehicle, horsepower matters. Do you want the high hp sports car or the low hp sports car? Do you want the low torque rock truck or the one with highest available torque? Yeah, me too.
Now if you want to talk about peak hp and torque vs hp and tq at low rpm, Iām all ears.
No, same weight vehicle, horsepower matters. OP was looking at two cars and only knew their horsepower figures. Based solely on that, OP is taking the rock truck racing. My comment was meant to explain that you need to know more so,
yes, being a fellow gearhead Iām happy to talk about that with you, but I figured it might be a bit of information overload for OP.
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10-4. I assumed (perhaps mistakenly) that these two cars they are considering were similar cars from competing brands, similar size, weight, etc. Iāll admit, I wouldnāt know a Mazda 3 or an Electra GT if I saw one.
I havenāt been a real big fan of DI because of the" all too known carbon build up issues" but if manufacturers can admit there is an issue and then design a engine and maintenance schedule that makes it reasonably economical to deal with it, then DI makes a lot more sense. ā¦ ($200 every 50k Is way reasonable IMO for the added benefits of DIā¦ I dont think your getting that kind service currently with a Vdub or Audi though.
Lots of manufacturers are doing combo direct injection and port injection. Port injection is done mainly to prevent the coking, I guess.
I say ālotsā. I believe Toyota is doing this, I know Ford is on the newer (2018 and up) F150ās.
Yep, there are Hybrid systems that deal with the problem but with those systems you have two fuel injectors per cylinder making it slightly more convoluted ie more hardware and software solutions to sort out the proper ratios. However with straight DI and a well thought out engine design in order to minimize the expense of the inevitable service costsā¦ DI makes more sense to meā¦ ājust tonight thoughāā¦ Iām sure ill change my mind tomorrow when iām less āinfluencedā
Mazda introduced āSkyActive-Xā now, where direct injection is combined with port injection to make for the stable super-lean burn using compression ignition.
Quite interesting concept and it is using two injectors per cylinder not as a band-aid, but as a way to get to the totally different ignition type.
The āEngineering Explainedā channel on the YouTube just put up a video on the SkyActiv-X and how it could be adapted to a Rotaryā¦ Pretty cool for sure. Mazda is doing some pretty interesting stuff.
My 2012 Camry SE with 100,000 miles is just as sound and comfortable as any foreign car. It rides a little harder because it has the sport suspension. It gets 27 MPG in the summer and 25 MPG in the winter driven locally. I get 31 MPG on highways. It handles sharp curves like being on rails and has 178 HP and 170 ft. Lbs. of torque. Tires and brakes last a long time. The front end holds its alignment and the leather interior is very comfortable. I only have to use regular gas. It also is cheaper to buy than a Bimmer.
Thatās weird, I always thought of Toyota Camry as a foreign car.
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Iāll throw my vote for the Mazda 3, but I own a Mazda Cx-7, so Iām a little biased on how good Mazdas are.
With a budget of $20k, you might be able to get a leftover brand new 2018 model for that price and still have all the warranty on it. I see several 2018 Mazda 3s in various trim levels for $20k or under at the dealership I bought my Cx-7 from.
Camrys and Bimmers are made in the US. Buicks and Volvos are made in China. The companies might be foreign but the cars are international.