If you want an e-bike that positively sprays tech out you, try the Volt Axis on for size. It takes the GoCycle GS's combo of folding, lightweight frame and disk brakes and adds automatic gears, if you please. These react to your speed and pedalling effort. So you automatically gear down when you stop at traffic lights – although what self-respecting cyclist does that? – and then back up as you accelerate.
Another style is the recumbent bicycle. These are inherently more aerodynamic than upright versions, as the rider may lean back onto a support and operate pedals that are on about the same level as the seat. The world's fastest bicycle is a recumbent bicycle but this type was banned from competition in 1934 by the Union Cycliste Internationale.
This article did a good job of trying to justify the assist speed limits but fell short of detailing how that can ever be effectively enforced. In reality the only enforcement that is going to work is applied speed limits to use of bikes and ebikes. For example, it makes sense that a bike lane on a street that the speed limit of vehicles is the speed limit of the bikes/ebikes. On sidewalks and shared pedestrian paths the speed limit probably does need to be in the 15-20mph range to match traditional bikes speeds on those paths.
It appears Tennessee has not passed any legislation that applies to electric bicycles. Some people think the laws pertaining to a Motorized Bicycle should be used for an electric bicycle. However, a Motorized bicycle would be a gasoline powered device per state law as it is defined as "means a vehicle with two (2) or three (3) wheels, an automatic transmission, and a motor with a cylinder capacity not exceeding fifty cubic centimeters (50cc) which produces no more than two (2) brake horsepower and is capable of propelling the vehicle at a maximum design speed of no more than thirty miles per hour (30 mph) on level ground." 
"Bicycle" means either of the following: (1) A device having two wheels and having at least one saddle or seat for the use of a rider which is propelled by human power. (2) A device having two or three wheels with fully operable pedals and an electric motor of less than 750 watts (one horsepower), whose maximum speed on a paved level surface, when powered solely by such a motor while ridden, is less than 20 miles per hour.
As of 2008 a standard class C license, proof of insurance, and registration (annual fee: $9.00) are required for operation of any motorized pedalcycle in Pennsylvania. Additionally, there are strict equipment standards that must be met for operation, including: handlebars, brakes, tires/wheels, electrical systems/lighting, mirrors, speedometer, and horns/warning devices.
In China, e-bikes currently come under the same classification as bicycles and hence don't require a driver's license to operate. Previously it was required that users registered their bike in order to be recovered if stolen, although this has recently been abolished. Due to a recent rise in electric-bicycle-related accidents, caused mostly by inexperienced riders who ride on the wrong side of the road, run red lights, don't use headlights at night etc., the Chinese government plans to change the legal status of illegal bicycles so that vehicles with an unladen weight of 20 kg (44 lb) or more and a top speed of 30 km/h (19 mph) or more will require a motorcycle license to operate, while vehicles lighter than 20 kg (44 lb) and slower than 30 km/h can be ridden unlicensed. In the southern Chinese cities of Guangzhou, Dongguan and Shenzhen, e-bikes, like all motorcycles, are banned from certain downtown districts. There are also bans in place in small areas of Shanghai, Hangzhou and Beijing. Bans of "Scooter-Style Electric Bikes" (SSEB) were however cancelled and in Shenzhen e-bikes may be seen on the streets nowadays (2010–11).
At the top end, the 20mph speed limit isn't an absolute, like the speed of light. It's just the most you'll get from the motor. I was able to get it up to 28mph on a flat road (there are no other roads where I live) in Turbo mode and 8th gear, but it took hard work to get there and maintain the speed. The easiest comparison is my mountain bike, where I've hit 23mph on that same stretch of road—and that took a heck of a lot of effort. Exactly how much effort does it take to ride? I have a 15-mile route that I ride on both my mountain bike and cyclecross bike. According to my Apple Watch, I generally burn around 1,400 or so calories on a brisk ride. I'll probably average around 13mph or so on my Marlin and between 16 and 17.5mph on my XO2. I averaged 14.9mph and burned a hair over 1,000 calories with the Bulls Cross E8.
X-Treme is a very well-known distributor of electric scooters and electric bikes with really great customer service. They offer a number of great budget electric bikes, and one of them is Catalina Beach Cruiser. Powered by 500W rear hub motor, this e-bike can conquer almost any terrain. The frame of this bike is 100% hand-welded aluminum, with a step-though design. The top speed on this bike is about 20 mph, with the range of up to 60 miles on pedal-assist mode. The battery pack is 48V LiPo4. This e-bike is an absolute joy to ride. Even more now, with an all new zero resistance rear hub motor with an automatic clutch. This makes riding without power a breeze and you will feel no resistance from the motor. Seat is large and very comfortable, with dual springs for smooth ride. It also comes with a basket, which is a must have if you plan on going for groceries or running errands on this bike.
My one complaint is the bike’s weight. This sucker is heavy! The aluminum frame looks light, but the the hub motor (4 pounds) and battery (5 pounds) add up. The bike’s total weight is 39 pounds, which is about average for e-bikes but not something you’d want to lug around all day. “This is not a solution for everybody,” Miller admits. “If you live in a fifth floor walkup this is probably not going to work.”
There are individuals who claim to have lost considerable amounts of weight by using an electric bike. A recent prospective cohort study however found that people using e-bikes have a higher BMI. By making the biking terrain less of an issue, people who wouldn't otherwise consider biking can use the electric assistance when needed and otherwise pedal as they are able. This means people of lower fitness levels or who haven't cycled in many years can start enjoying the many health benefits E-bikes have to offer.