CES 2015 wrapped up on January 9 in Las Vegas. As usual, companies showcased plenty of promising new products, but there were also wacky ideas like self-adjusting smart belts and Android-powered smart cookers. Let's filter out that noise and discuss three main themes at CES that tech investors should know.

Cheaper and smarter wearables
Wearables like smartwatches and fitness bands are often considered a way for smartphone and GPS makers to diversify away from their saturated core markets.

Research firm, Canalys, forecasts that annual smartwatch shipments worldwide will soar from 8 million in 2014 to 45 million by 2017. Gartner believes that smart wristband (Jawbone UP, FitBit Flex) sales will fall from 20 million units in 2014 to 17 million this year due to competition from cheap smartwatches, but sales could rebound in 2016 as low-end wristbands and smartwatches converge.

Of all the wearables introduced at CES, Lenovo's (OTC:LNVGY) $89 Vibe Band VB10 could be the most disruptive. Set for an April release, the VB10 packs in fitness tracking (steps, distance, calories, and sleep) features along with notifications for calls, SMS, Facebook, and Twitter. Lenovo claims that the VB10 can last for a week on a single charge thanks to its low-power e-ink display. The VB10 will be compatible with iOS and Android 4.4 devices and could disrupt the current market for health-tracking smartwatches, which mostly cost between $100 to $300.

Lenovo's VB10. Source: Lenovo

Smarter Cars
Meanwhile, automakers showcased new ways to monitor and enhance their vehicles with mobile tech. General Motors will equip select 2016 Chevrolet vehicles with onboard 4G LTE Wi-Fi and an OnStar RemoteLink mobile app which can alert owners about potential problems. Volkswagen's Audi introduced the sleek Audi Tablet, which provides passengers with more personalized in-vehicle infotainment.

Yet Daimler's (OTC:DDAI.F) Mercedes-Benz stole the show with its autonomous F015 Luxury in Motion concept car. In self-driving mode, the F015's steering wheel retracts and the driver's seat rotates backwards, so he or she can mingle with passengers. Passengers can also interact with the embedded touch screens which cover its interior.

The F015's interior. Source: Mercedes-Benz

The F015 is notably hydrogen-powered -- a major vote of confidence for the clean energy standard championed by Toyota and other Japanese automakers -- and can travel 680 miles without refueling.

The F015's exterior. Source: Mercedes-Benz

Mercedes claims that autonomous vehicles like the F015 will be commonly seen all over the world by 2030. But today, fully autonomous vehicles are far too pricy to be practical. Google's self-driving car, for example, is outfitted with over $250,000 in equipment. However, companies like MobilEye are installing semi-autonomous systems (staying in a single lane and auto-braking for pedestrians) for less than $1,000.

The big 4K team-up
Lastly, television manufacturers continued to promote 4K/Ultra HD TVs (which have four times the resolution of 1080p HDTVs) as the future of home entertainment.

That's because HDTVs are now such low-margin products that major players Philips, Panasonic, and Sony (NYSE:SNE) have respectively exited, scaled down, and spun off their TV businesses. Meanwhile, tech review sites like CNET claim that the difference between 4K and 1080p can be difficult to notice for average consumers.

To address these problems, Samsung (NASDAQOTH: SSNLF), Sony, Dolby (NYSE:DLB), Fox (NASDAQ:FOX), and other companies introduced the UHD Alliance -- which will standardize terminology to accelerate consumer adoption -- at CES. Unfortunately, working together will be easier said than done. Top 4K TV manufacturers like Samsung are inking exclusive 4K content deals to lock out competitors. At CES, manufacturers unveiled arguably gimmicky features like "quantum dots" (nanocrystals for richer colors), HDR (high dynamic range, aka clearer contrast), and curved displays -- all of which go against the Alliance's promise of "standard terminology."

A curved Samsung 4K TV. Source: Samsung

To make matters worse, 4K prices have already declined dramatically. Back in April 2013, Seiki launched a 50-inch 4K TV for $1,500. Last September, Vizio launched a $1,000 50-inch 4K TV, roughly matching the price of Samsung's 50-inch 1080p HDTV. This means that consumers win, but 4K TV manufacturers will continue to struggle with low margins.

The road ahead
Wearable devices, smart cars, and 4K TVs are merely three categories of products seen at CES 2015. However, all three highlight key trends in consumer electronics, and tech investors should take a closer look at the aforementioned companies to tap into that growth.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.