You can have both things. The issue is the Applefication of car maintenance, where manufacturers make it impossible to repair so they can force you to go the shop.
You can have both, but with these regulations? Not on your life. The fact that emission regulations change annually or at least progressively, squeezes engineers into a corner where they have to innovate at a rate so fast, that refining a design becomes impossible. Take the Euro Emissions Standard for example. They already have a chart setup for future regulations with that Euro 1,2,3,4,5,6,7 etc. bullshit. The other main problem is patenting. Patenting makes it so competitors have to come up with their own systems instead of following logic and coming up with unified solutions. Back in the golden days of modern design (between the 30s-60s), form used to follow function. Today form has to follow restrictive laws and regulations and stupid consumer choices.
This is why cars nowadays have to have EGR, SCR or DPF, and exhaust cooling systems for exhaust emissions. Hell there's cars that have all four, like the new Golf TDIs. They have to have VVT, DI and PI, turbochargers, variable-geometry turbochargers, water charged intercoolers, and now we have Volvo semis that have turbocompounds. Then there's regenerative braking, God I hate that stuff! The new hybrids are required to have EVAP systems (That stupid buzzing you hear cars make when they are shut off) where the car has to capture in the evaporated gas from the gas tank and reinject it back into the cylinders. You can't have all these systems under the hood with easy access, so you are faced with the problem of compact design issues where getting to, say, an oil filter requires the removal of the battery or the air intake box, or both.
Don't get me wrong, I like technology and innovation. I like driving cars that have dual-clutch transmissions that make you feel like you're in a race car. I like innovative solutions like active grille curtains that close up to reduce Cd when the engine is cool enough. I like the environment and protecting it, but what's taking place today is we are low-key moving backwards. Cars keep getting bigger, heavier, more complex, and the coefficients of drag keep on increasing. We went from classic Bugattis and egg/tear drop shaped cars like the 300SL Gullwing, Thunderbird, Porsche 356, and the incredible air-cooled VW Beetle, to brick shaped heaps of trash like the G-class, Jeep Wrangler, Humvees, Escalades, and minivans. The consumer is parly to blame here. They want bigger and higher and Apple Carplay and AI and self driving and seven seaters and 20 airbags and 20 speakers and 700km range batteries that weigh more than the entire car itself. I mean have you seen the new Hummer EV? It weighs over 4 tons!
So in summary, I think efficient low-emission cars are possible without complex engines and their emission control systems. Cars can be made lighter and more aerodynamically efficient, but will they ever? Probably not. Maybe we will get an economy of rickshaws/city cars going in the near future and finally get access to concepts like the VW L1 and Nils and some of these urban concepts we see in Canton fair, but for the time being, we are stuck with overpriced shitboxes.