OutRun Online Arcade

Basically the aim to these time attack achievements is obviously keeping your speed up.
So basically keep off the grass and the fences, though 1 or 2 slip-ups isn't too bad. Basically you need to average about 58 seconds for each stage. I was getting about 56 seconds for the first maybe 6 or 7 then 58 n 59 seconds for a few of them then ended with some 1 minute times.
Got 14:28

Hope this helps

Just adding onto to Nath360skillz’s Solution, this achievement is a little under the difficulty of Cardiogram but still very challenging, in my opinion, the second hardest in the game. For this you have to complete Time Attack 15 Course Continue Mode in under 14:30:00. When I first tried for this achievement, I kept running out of time 2/3rd of the way through, same as going for the Risky Ride achievement. The trick is to have the difficulty set to Very Easy. This allows more time, and you do not need to worry about not finishing. You will have plenty of time to at least finish for a game complete towards Frequent Flyer, but you still need to beat the target time, which is very challenging like I said above.

Some pointers are to definitely keep your speed up, try for less than 58:00 seconds for each of the first 10 stages, after that they get kind of difficult, and are near impossible to complete in less than 1 minute. You might have some 1:01:00-1:02:00, try not to get over a 1:02:00 time on some of those stages. Now the last stage is very quick, able to be done in less than 55:00 seconds, it is possible.

You must not mess up, this is the most important thing! Keep off the grass, drift when you absolutely need to, this saves you from smashing into the walls as the tuned cars are a little faster. Some corners you’ll need to learn not to drift on, because they can be taken faster if you don’t.

I hope this solution helped! Leave a comment letting me know if there is any room for improvement! Thanks.